Part I Vader Post Mustafar- A - His Diminish In Power

contrary to the popular opinion, Vader's power wasn’t heavily decreased via his Mustafar injuries, even when he was at his lowest, burning after his limbs were chopped off, he was more powerful than his nemesis, Obi-Wan Kenobi:

As Anakin struggled to raise his head from the smoldering sand, his eyes blazed with fury as he glared at Obi-Wan. I won’t die like this! I’m still stronger than you!

- The Death Star

This was further solidified when George Lucas himself gave us a quantifiable amount of how much Vader has truly fallen:

“Anakin, as Skywalker, as a human being, was going to be extremely powerful. But he ended up losing his legs and an arm and became partly a robot. So a lot of his ability to use the Force, a lot of his powers, are curbed at this point, because, as a living form, there’s not that much of him left. So his ability to be twice as good as the Emperor disappeared, and now he’s maybe 20 percent less than him.

--George Lucas, Vanity Fair Magazine

Lucas while completely distinguishing Anakin’s potential and Vader’s current power in his phrasing (Curbed at this point, Now he is maybe 20% less than him) right after his gruesome defeat in Mustafar. (he ended up losing his legs and an arm) outright states Vader possesses 80% of Sidious’s full power.

One of the arguments that have been made against this statement is that it refers to Suit Vader’s potential, which is not only true when we see Lucas distinguish between Anakin’s potential and Vader’s power which I addressed, its contradicted by C-Canon sources greenlighted by George after the Prequel Trilogy too, where Vader is portrayed as having a higher potential than Sidious .

Vader knew all about midi-chlorians, of course—he personally had the highest count per cell ever recorded, more than twenty thousand. More than Yoda, and, he knew, more than his erstwhile Master, Kenobi. Which meant that, potentially, he could have a stronger connection to the Force than anyone.

--Death Star

The Rebels were turning out to be more troublesome than many had expected. The Emperor had known it would be thus, of course; the resistance had not been a surprise to him. The Emperor was completely in concert with the dark side of the Force. He was the most powerful Sith who had ever existed.

As would Vader be, someday.

--Death Star

There would come a day, however, when they would be equals.

--Dark Lord Rise Of Darth Vader

Another argument made against this quote is that it's unquantifiable, that the 20% gap can be quite large and can make Vader fall tiers below his Master's.

To address this, we must look at when Lucas made this comparison, During the production and theatrical release of Revenge Of Th Sith, when he and Nick Gillard came up with a power leveling system:

"George Lucas works on a system of levels. So, on The Phantom Menace Obi-Wan would have been like a level six or seven. Now that we're on Episode III he's actually a level eight. When you move up the levels, it affects the style of fighting."

- Nick Gillard, Homing Beacon #126

"In this one, Anakin becomes a level nine. George knows the levels. George talked about levels and how it works.

- Nick Gillard, ROTS DVD commentary

Gallery

Lucas worked on a system of levels to distinguish power between his characters, not only he work on this system, he knows it inside and out and his comment on Suited Vader’s power is most certainly tied to how he sees his other characters:

But it's not like a black belt, it's more like a ricter scale. So the difference between eight--Obi is an eight--and a nine is enormous."

- Nick Gillard, ROTS DVD commentary

The gap between tiers is massive, it's like a Richter scale. This is what the mentioned scale looks like:

Vader’s power is only shy of 20% of Darth Sidious who is confirmed tier 9, Comparing it to the Richter scale Vader being 80% of The Emperor will still grant him the power and tier of a 9 (the compared amount being 16 trillion KG TNT and giganticly above the tier 8 which is 60 billion), making it impossible that if the gaps are truly massive, Vader falling tiers below his master.

Now the question is, is this comparison valid? Does the Star Wars Expanded Universe follow this disparity in power between 8s and 9s? the answer is yes.

While Star Wars mythos has a habit of dramatization and the heavy contextualizing battle between Force Users making it very hard to quantify the difference in power, we do have an instance of direct power comparison that shows the massive gap between the tiers:

In this particular instance, we see a tier 9, Darth Sidious, goes into a blade lock with two of the most physically gifted power duelers in the mythos, Darth Maul and Savage Oppress.( both can be easily confirmed as solid 8s)

It should be noted this is a straight-up none contextual instance, all the combatants are fresh and full of reserves and the brothers are augmenting themselves to their maximum capabilities because they know the threat that is Darth Sidious. The only context to this scene only benefits the gap more, that the Emperor is not going all out and is confirmed to be toying with them.

So Darth Sidious, a Luca’s tier 9, easily overpowered the combined strength of Darth Maul and Savage Oppress, two solid 8s, in a blade lock while being massively inferior in physical strength and not going all out. That would mean that The Emperor is way more than twice as powerful as them meaning he possesses way more than 200% the power of a good tier 8 in the Star Wars expanded universe meaning Lucas has bent the Star Wars mythos to his tiering and the gap he envisioned, making it further impossible for post-Mustafar Vader being even close to a tier 8.

Now I know what you are wondering, But how can that be? Vader doesn’t display anything even close to Palpatine during that time, so how can he rival him in power?

Well, while Vader’s actual raw power wasn’t heavily decreased, he has a lot of hindrances that make his applicable power come up short, such as his Suit and his mentality which has curbed his connection to the Force. Let's go through these hindrances with the help of my good friend BreakofDawn .

Part I - B: Vader’s abilities at this point

To begin, it is important to stress for the purposes of this section that Purge #1 takes place around a month after Revenge of the Sith. With the declaration of Order 66 in 16:5, Purge takes place in 16:6:

This is particularly significant due to Vader’s physical state at this point. In The Rise of Darth Vader, Vader goes into considerable detail regarding his body at this point in time:

Where Darth Sidious had gained everything, Vader had lost everything, including—for the moment, at least—the self-condence and unbridled skill he had demonstrated as Anakin Skywalker.

Vader turned and moved for the hatch.

But this is not walking, he thought. Long accustomed to building and rebuilding droids, supercharging the engines of landspeeders and starfighters, upgrading the mechanisms that controlled the rest of his artificial limbs, he was dismayed by the incompetence of the medical droids responsible for his resurrection in Sidious’s lofty laboratory on Coruscant.

His alloy lower legs were bulked by strips of armor similar to those that lled and gave form to the long glove Anakin had worn over his right-arm prosthesis. What remained of his real limbs ended in bulbs of grafted esh, inserted into machines that triggered movement through the use of modules that interfaced with his damaged nerve endings. But instead of using durasteel, the medical droids had substituted an inferior alloy, and had failed to inspect the strips that protected the electromotive lines. As a result, the inner lining of the pressurized bodysuit was continually snagging on places where the strips were anchored to knee and ankle joints.

The tall boots were a poor fit for his artificial feet, whose claw-like toes lacked the electrostatic sensitivity of his equally false fingertips. Raised in the heel, the cumbersome footgear canted him slightly forward, forcing him to move with exaggerated caution lest he stumble or topple over. Worse, they were so heavy that he often felt rooted to the ground, or as if he were moving in high gravity. What good was motion of this sort, if he was going to have to call on the Force even to walk from place to place! He may as well have resigned himself to using a repulsor chair and abandoned any hope of movement.

The defects in his prosthetic arms mirrored those of his legs. Only the right one felt natural to him—though it, too, was artificial —and the pneumatic mechanisms that supplied articulation and support were sometimes slow to respond. The weighty cloak and pectoral plating so restricted his movement that he could scarcely lift his arms over his head, and he had already been forced to adapt his lightsaber technique to compensate.

-

What’s more, the sleeves of the bodysuit didn’t hug the prostheses as they should, and the elbow-length gloves sagged and bunched at his wrists. Gazing at the gloves now, he thought: This is not seeing. The pressurized mask was goggle-eyed, short-mouthed, short snouted, and needlessly angular over the cheekbones. Coupled with a a ring dome of helmet, the mask gave him the forbidding appearance of an ancient Sith war droid. The dark hemispheres that covered his eyes filtered out light that might have caused further injury to his damaged corneas and retinas, but in enhanced mode the half globes reddened the light and prevented him from being able to see the toes of his boots without inclining his head almost ninety degrees.

Listening to the servomotors that drove his limbs, he thought: This is not hearing. The med droids rebuilt the cartilage of his outer ears, but his eardrums, having melted in Mustafar’s heat, had been beyond repair. Sound waves now had to be transmitted directly to implants in his inner ear, and sounds registered as if issuing from underwater. Worse, the implanted sensors lacked sucient discrimination, so that too many ambient sounds were picked up, and their distance and direction were difficult to determine. Sometimes the sensors needled him with feedback, or attached echo or vibrato effects to even the faintest noise. Allowing his lungs to ll with air, he thought: This is not breathing. Here the med droids had truly failed him. From a control box he wore strapped to his chest, a thick cable entered his torso, linked to a breathing apparatus and heartbeat regulator. The ventilator was implanted in his hideously scarred chest, along with tubes that ran directly into his damaged lungs, and others that entered his throat, so that should the chest plate or belt control panels develop a glitch, he could breathe unassisted for a limited time.

-

Already he had experienced moments of claustrophobia—moments of desperation to be rid of the suit, to emerge from the shell. He needed to build, or have built, a chamber in which he could feel human again … If possible. All in all, he thought: This is not living. This was solitary confinement. Prison of the worst sort. Continual torture. He was nothing more than wreckage. Power without clear purpose … A melancholy sigh escaped the mouth grille. Collecting himself, he stepped through the hatch.

-

Without revealing his distress at being unable to maintain the kneeling posture, Vader said: “What are your orders, Master?”

(Source: Rise of Darth Vader).

As you can see above, Vader at this point is little more than a barely moving carcass. From tall boots that were an “ill fit for his artificial feet” and which “canted him slightly forward, forcing him to move with exaggerated caution lest he stumble or topple over” to hearing that “registered (sounds) as if issuing from underwater” and made “distance and direction...difficult to determine”, Vader is incredibly hindered by his prosthetics at this point. While they offer him great strength and even greater durability, they are slow, uncomfortable, sluggish and foreign to a Vader who still thinks like Anakin to an extent at this point.

To give you an idea of how these prosthetics limited Vader even further: beyond having to “adapt his lightsaber technique to compensate”, Vader expresses frustration at how these cybernetics actually hinder him at this point, claiming that he’ll have to call on the Force even to walk from place to place”. At this point in time, Vader struggles to even move from one side of the room to another.

Part I - C - Vader's Mental Health

I’ve briefly covered that above, but I plan to elaborate on it here. First, Vader had almost no confidence left in his abilities:

Where Darth Sidious had gained everything, Vader had lost everything, including—for the moment, at least—the self-confidence and unbridled skill he had demonstrated as Anakin Skywalker.

(Source: Ibid).

After his humiliating defeat on Mustafar, Vader feels trapped, isolated and like a stranger in his own body. Unlike Anakin, who had boundless confidence that bordered on arrogance, Vader has completely lost that and is building himself back up from the lowest point he has ever reached.

What’s worse, is that Vader was even unsure about his place within the Force:

While he retained his knowledge of the Jedi arts, he felt uncertain about his place in the Force; and while he had taken his first steps toward awakening the power of the dark side, he felt uncertain about his ability to sustain that power. How far he might have been now had fate not intervened to strip him of almost everything he possessed, as a means of remaking him

(Source: Ibid)

Interestingly is that Vader is consumed by self-doubt and uncertainty. Vader has, for all intents and purposes, cut himself off from accessing anything even remotely comparable to what he could wield as his Knightfall or Mustafar. As we’ve seen before, even small seeds of doubt can massively impact a Force user’s abilities:

The Hero of Tython: “Malgus’s lightsaber form was flawless, but he let anger and desperation cloud his fighting. He faltered, and I followed through.”

-

The Voidhound: “There I was, blaster in hand, sidestepping Force attacks, when Malgus lost his cool. But not me. I took the shot, and that’s all she wrote.”

In the case of Malgus, this doubt and uncertainty made him vulnerable to Force attacks and knockbacks, were before the strike team had been completely unable to phase him with them:

As both these examples show, doubt and uncertainty can massively impede a Force user as powerful and masterful as Malgus, giving the strike team the opening they needed just to knock him off the walkway.

As this suggests, Vader would have been emotionally hindered and unable to bring his full strength to bear at this point, feeling clumsy, cumbersome, and like a cripple.

Part II – Vader’s Rise In Dark Times - A - Adaptation and Growth

After years, Vader started adapting to his suit and perfecting his connection to the force to tap in to his true raw power:

Over time Vader has advanced in his ability to manipulate the dark side of the Force, and has used it to sustain his own damaged body as well as to persuade opponents of his will. Under the Emperor's tutelage, Vader learns to kill with mere suggestion.

-- Star Wars Visual Dictionary

As Darth Sidious's apprentice, Vader continues to expand his knowledge and the power of the dark side.

-- Force And Destiny Core Rulebook

More important, Vader's bloodlust had been appeased; replaced by self-possession of a sort he had never before experienced. It was as if he had crossed some invisible threshold to a new world. He could feel the power of the dark side surging through him like an icy torrent. He felt invulnerable in a way that had nothing to do with his durasteel prostheses, his suit of armor and gadgets, which now seemed little more than an outfit. And it had taken a Jedi–yet another Jedi–to usher him over that threshold.

--

Sidious was pleased. Vader had done well. He had sensed the change in him, even in the brief conversation they had had following the events on Kashyyyk. Now that Vader had begun to tap deeply into the power of the dark side, his true apprenticeship could begin. The Jedi were incidental to him. He was covetous of the power Sidious wielded and believed that one day they would be equals.

-- Dark Lord: The Rise Of Darth Vader

Destroyer of the Jedi Order, the Emperor's personal enforcer, Darth Vader, had overcome the physical restrictions from the injuries he had received in his duel with Obi-Wan Kenobi, and from the bulky armor, he had to wear to stay alive.

-- The Official Starships And Vehicles Collection 8

“This is a fight you cannot win, Darth. Your power has matured since I taught you, but I too have grown much since our parting. If my blade finds its mark, you will cease to exist. But if you cut me down, I will only become more powerful. Heed my words.”

-- A New Hope

He started to regain his confidence and dismissed his hindrances from before, plus he massively grew throughout the decades until the events of ANH:

Over time Vader has advanced in his ability to manipulate the dark side of the Force, and has used it to sustain his own damaged body as well as to persuade opponents of his will. Under the Emperor's tutelage, Vader learns to kill with mere suggestion.

-- Star Wars Visual Dictionary

As Darth Sidious's apprentice, Vader continues to expand his knowledge and the power of the dark side.

-- Force And Destiny Core Rulebook

Even his own generals could not escape Vader's wrath, and as time went by, the Sith's powers grew even stronger.

-- The Story Of Darth Vader

"My Master seems pleased; his apprentice grows ever stronger."

-- Galactic Battlegrounds

Between Lord Vader and the Imperial Inquisitors (and a handful of independent Jedi Hunters), the dark side grew stronger and stronger.

--The Dark Side Sourcebook

All his life he had been trained to turn fear into anger, and anger into power. It was no different, he realized, for Darth Vader. Where else could Lord Vader look for increased power than to the Emperor himself? People were either predators or prey. That was one of the most basic rules of life. Together, Darth Vader and his apprentice would ensure that their joint power only increased.

-- The Force Unleashed

While the rise of Vader from the ashes of his defeats is very impressive, the events of Mustafar still gave him his major weakness.

Part II - B – Vader’s PTSD

Whenever Vader is reminded of his past he automatically becomes far weaker than he normally is, for example, Vader was toying with and wrecking an out of shape Ferus Olin when Vader was in a good mental state

Vader crossed the distance between them before the old man even had time to draw his weapon. I could kill him with a single blow, Vader thought. But there was no hurry. And he had to admit, he was curious. Ferus had become such a decrepit human specimen, paunchy and sad. Soft. It would be interesting to let him believe he could still put up a fight.

Vader swung his blade down. Ferus met it solidly. There was a dull hum as the red and blue blades clashed.

“Your technique has become lazy,” Vader observed. He parried a blow, almost as an afterthought.

Ferus didn’t reply. He was breathing heavily, gasping with each lunge and thrust. Vader deflected every strike with little more than a flick of the wrist.

--Uprising

But the moment Vader is reminded of the word Anakin, Vader automatically becomes weaker and starts struggling against Feus

You think no one can match you, right? Same old Anakin.”

“Anakin is dead!” Vader roared, and struck with his full power. Time to end this game.

But Ferus somehow evaded the blow — and then danced away from the next one, and the next. The blue blade whirled and spiraled through the air, matching Vader strike for strike, blow for blow.

It was that name. That was the only explanation. Even the sound of it had somehow thrown him off balance.

--Uprising

While a much weaker Vader was blitzing and stomping a much younger and much more powerful Ferus Olin why the latter was substantially amped , this shows how much weaker Vader becomes on a single stroke of PTSD

He is a former associate, yes, but --"

It happened before he could get out another word. Faster than an eyeblink. Faster than he'd seen anyone move, anyone except Yoda.

The lightsaber hadn't been there, and then it was, and the lightsaber was a blur. Vader moved without seeming to move, and the lightsaber sliced into Roan, straight into his chest. Straight into his heart.

-- Last Of The Jedi: Secret Weapon

This was it, then. The final confrontation.

He was ready. His rage was ice and fire.

He charged.

His first blow was easily parried. He came at Vader again. Again. Circling, jumping, vaulting past him, turning. Each time his lightsaber came toward him, it was eilher deflected in a shock that ran up his arm, Vader simply wasn't there.

---

Ferus leaped over a gaping hole in the floor and attacked Vader again, but his lightsaber cut through empty air.

-- Last Of The Jedi: Reckoning

another example is the duel with Ben Kenobi , where Vader starts having flashbacks and starts getting PTSD making him substantially weaker

He did not wish them to interfere, but even to warn them off would take concentration that he could not afford at the moment. Should his attention falter, Obi-Wan could kill him in the blink of an eye.

- Death Star

There had always been in Vader a small bit of worry about this day. Not much; just a trace. He had been sure, in his youthful arrogance, that he had been stronger, had been better than the Jedi Knight who had been his teacher, and the memory of what Obi-Wan had done to him would never be erased. He had been a superior fighter even when he had been Anakin Skywalker, and yet Obi-Wan had defeated him.

Could he win now?

Vader's mental Hindrances: Post Traumatic Stress Disorder, surrounding the fact that he was remembering his defeat.

There he was. After so much time and across so much space, the hooded figure of Obi-Wan Kenobi, his former Master and friend, stood right in front of him. He had aged; his face was lined, his beard white. It was impossible not to remember vividly the last time they had seen each other, when his Master had crippled him and left him to die on the fiery banks of a river of molten rock, light-years from here. Now his anger smoldered in him like the banks of that coursing stream of lava. You should have killed me then, Obi-Wan

Now, why is it that Vader’s Post Traumatic Stress Disorder hinders his Force power so much? Well PTSD hampers one’s motor skills and focus:

Doctors call these “arousal symptoms.” They can make your emotions more intense or make you react differently than you normally would. For example, if you're a careful driver, you might start driving too fast or be super-aggressive on the road. Irrational, angry outbursts are very common.

Many find it hard to focus. Feelings of danger and being under attack can ruin concentration and keep you from finishing tasks you do every day. This can also lead to trouble sleeping, whether you're having nightmares or not.

--WebMD

These hindrances, especially the lack of Focus and uncontrolled rage, massively hampers one’s power in the SW mythos:

Generally, this was done by broadcasting strong emotions while thinking about something else. It was a curious technique, but it seemed to be effective in blinding Jedi. Whether guilt, lust, fear - they act as mental interference, making finding the true intentions of the broadcasting meatbag difficult. Obviously, a Force Sensitive broadcasting such emotions puts themselves at risk of not using the Force "properly," since to use it seems to require an inner calm that most meatbags do not possess. As much as the Jedi could not use such a technique, the Sith Lords cannot use it for much the same reasons - such passions as guilt, lust, and fear are rarely strengths to the Sith code.

- The Knights of the Old Republic

Yoda had told Luke that electrical shocks, applied at different intensities and at irregular but frequent intervals, would prevent a Jedi from concentrating, from channeling the Force. They could render a Jedi helpless.

But Yoda had never told Luke that emotional shocks could do the same thing.

They could. And just as no amount of self-control would allow a Jedi to ignore the effects of electrical shocks on his body, neither could self-control keep Luke safely out of his memories

-- Legacy of the Force: Fury

Gallery

This condition has cursed Vader throughout his life and the evidence for it is unignorable, be it his cruel punishments for a single misstep from his commanders, his rage outbreaks, his suicidal thoughts, and memories and flashbacks he has from Mustafar during his days as nightmares, without a doubt shows his severe PTSD condition and it's responsible for his some would call low showings.

Part III - The ANH Duel- A- Ben Kenobi

Ben Kenobi, is often an underrated part of the Star Wars, he is depicted as a threat to the whole Empire, including both Emperor Palpatine and Darth Vader,

Mysterious Hermit

Once a great warrior of the Old Republic, the mysterious Ben Kenobi is a Jedi Knight who lives in the Jundland Wastes. His vast powers and knowledge. of the Force make him threat to the Empire

-Star Wars Theatrical Program 1977

(Ben Kenobi, a once respected name in the galaxy, is now an outlaw in the Tatooine mountains. The shabby old desert rat of a man was, before the rise of the sinister Galactic Empire, one of the greatest warriors in the Old Republic. Even now, in his old age he can still be a threat to the Empire because of his very special powers.)

-Star Wars DK Ultimate Sticker Collection

and assisting the rise of the Emperor. Crushed by his failure. with the man who became Darth Vader, Kenobi retreated to Tatooine, watching over the young Luke Skywalker and waiting for the time to reveal Luke's birthright as the son of a Jedi. Kenobi's powers make him a threat to the Empire even in his elder years.

-Star Wars The Complete Visual Dictionary

Vader is stated to only be matched in the entire galaxy in the combative sense by none other than Ben Kenobi himself

Darth Vader possesses, aside from his extraordinary strength, strange extrasensory powers which he can use to probe mirds. Only one man is his match, his dreaded enemy Ben Kenobi.

-Star Wars Poster Monthly 1

While Vader is the only combative Match for Ben Kenobi in the entire universe, meaning that these two are combatively the best in the entire galaxy,

Only one other being can match Ben Kenobi's power the evil Darth Vader, who also has memories of times long past. In an epic confrontation, the two ancient adversaries do battle with laser swords to decide who will be the ultimate master. Ben Kenobi appears to die, vanishes into thin air, and leaves only his cloak behind him.

-Star Wars Poster Monthly 1

They both have supremacy statements in a Galaxy where Emperor Palpatine is present, and this Ben position was always the idea even in early concepts:

Ben can say that Luke is now a level 2 and Vader is a 4. 'I was a 6 and The Emperor is a 6, and he's on his way to becoming a 10.

and even Sidious is someone who fears the name of Ben Kenobi as of a New Hope, showing how monstrously powerful Ben Kenobi was in actuality

Ben Kenobi is a name that strikes fear into the heart of every evildoer in the Galaxy. Ben Kenobi was one of the greatest warriors of the Old Republic, fighting for honour and liberty. Then, when the

in addition Ben Kenobi is directly stated to be the most powerful jedi to ever live

"Put all sections on alert," Tarkin ordered through the com link. Then he turned to stare at Vader. "If you're right, he must not be allowed to escape."

"Escape may not be Obi-wan Kenobi's intention," Vader replied, struggling to control his emotions. "He is the last of the Jedi and the greatest. The danger he presents to us must not be underestimated-yet only I can deal with him." His head snapped around to stare fixedly at Tarkin.

"Alone

-Star Wars: From the Adventures of Luke Skywalker

Part II - B Ben Kenobi vs Darth Vader

people believe that Ben vs Vader was some kind of a massive anti feat for Vader, I will give you a different.....outlook on the merrier

Ben's reflexes were no worse than his younger self, he had not allowed them to grow dull at all.

It was fortunate for Ben that he had continued his Jedi exercises on Tatooine, that he had not allowed his reflexes to become dull.

--The Life and Legend of Obi-Wan Kenobi

Ben also had growth as much as Vader, or even more , as he is stated to have become much stronger combatively then ever before

“This is a fight you cannot win, Darth. Your power has matured since I taught you, but I too have grown much since our parting. If my blade finds its mark, you will cease to exist. But if you cut me down, I will only become more powerful. Heed my words."

-- A New Hope

Ben's power and studies didn't decrease at all even though the last Time Vader fought Obi-Wan was at Mustafar.

"He had assumed Obi-Wan's study of the Force had ended long ago, and that his powers had diminished over time. But Vader was wrong."

- A New Hope Junior Novelization.

Vader's mental hindrances: Paranoia surrounding The fact that he was more powerful on Mustafar but still lost

He did not wish them to interfere, but even to warn them off would take concentration that he could not afford at the moment. Should his attention falter, Obi-Wan could kill him in the blink of an eye.

- Death Star

Although he knew that he is even more powerful than he was Anakin Skywalker:

There had always been in Vader a small bit of worry about this day. Not much; just a trace. He had been sure, in his youthful arrogance, that he had been stronger, had been better than the Jedi Knight who had been his teacher, and the memory of what Obi-Wan had done to him would never be erased. He had been a superior fighter even when he had been Anakin Skywalker, and yet Obi-Wan had defeated him.

Could he win now?

Vader's mental Hindrances: Post Traumatic Stress Disorder, surrounding the fact that he was remembering his defeat which I addressed earlier how much that diminishes Vader's abilities.

There he was. After so much time and across so much space, the hooded figure of Obi-Wan Kenobi, his former Master and friend, stood right in front of him. He had aged; his face was lined, his beard white. It was impossible not to remember vividly the last time they had seen each other, when his Master had crippled him and left him to die on the fiery banks of a river of molten rock, light-years from here. Now his anger smoldered in him like the banks of that coursing stream of lava. You should have killed me then, Obi-Wan

Vader still parrying everything Obi Wan threw at him, even when he is trying to capitalize on Vader's speed and offguardnwss

Obi-Wan moved fast, lunging at Vader with his weapon, but the Dark Lord blocked the attack with ease. There was a loud electric crackle as their lightsabers made contact. Undeterred, Obi-Wan made a swift series of strikes, but each was parried by Vader.

-

Their lightsabers clashed again and again, and their duel carried on until they were just outside Docking Bay 327. As they moved toward the door that led directly into the hangar that contained the captured freighter, Vader heard the approaching footsteps of stormtroopers running toward his position. Vader's blade was crossed with his opponent's when Obi-Wan threw a glance into the hangar. Vader kept his eyes riveted on the Jedi. You won't get away from me this time!

- TR&FoDV

Vader was confirmed more powerful and forced ben to retreat and countered everything Obi-wan was throwing before Kenobi can do anything

Another exchange-four, five, six attacks and blocks-and Vader knew the old man was weakening. The Force might be strong in Obi-Wan, but the dark side was stronger in Vader. It let him anticipate his adversary's strikes and counter them almost before they began.

Obi-Wan knew it, too. He began a retreat, backing away, his lightsaber itself seeming weaker as he moved. Vader backed Obi-Wan past an open blast door leading to the forward dock where the Rebel freighter was being held under guard. The old man was obviously tiring. You're mine, old man, Vader thought.

- Death Star

Ben barely parrying Vader's blows

Ben catches Vader off-guard when Vader goes arrogant and lands the killing blow, yet Vader blocks everything before it could land

But just as he was ready to deliver the final strike, Obi-Wan managed a fast series of attacks, and Vader had to move quickly to avoid the strikes. Even as old and weak as Obi-Wan was, his technique was accomplished enough that a foolish move on Vader's part could still be fatal.

- Death Star

Vader easily blocked his strikes

Only a master of evil, Darth." With that, Obi-Wan stepped in and cut. Vader blocked the attack easily. Obi-Wan attacked again, and again, Vader blocked each strike. If the old man thought he could rattle him by attacking instead of defending, he was mistaken. Vader riposted, sped up his timing, and took the initiative, forcing the erstwhile Jedi to defend.

- Death Star

Not to mention , Ben was still a very formidable user of Form III , thus still holding the form advantage over Vader

Even in his elder years, Kenobi remains a formidable Form III practitioner.

Source: Insider 62: Fightsaber

so a pre-prime Vader was able to decisively beat the strongest Jedi of all time while being hindered by mental problems, having a form Disadvantage and fighting away from his general way of fighting, and having literal flashbacks during fucking saber combat

Part III - C Ben Kenobi was Amped

Ever since Ben began looking after Luke, Luke has become, for want of a better way of putting it, his connection to the Force. Everything Ben has, everything he is is now focused around protecting Luke.

Now, you might be asking how this is relevant, and how I’ve come to this conclusion. First off, let’s look at Ben’s fight with A’Sharad Hett:

"I cannot permit that," Ben said as he drew his light-saber. "You were a great Jedi, Hett, and the son of a great Jedi, but you have given yourself over to revenge. It stops here." Ben ignited his lightsaber.

Ben did not answer. He believed that the Tuskens could kill every settler on Tatooine and their hunger for violence would still be unsatisfied.

Taking Ben's silence as a negative response, Hett said, "Then blood calls for blood ! The settlers will be forced to abandon the land . . . or be buried beneath it!"

"You will have a Jedi funeral, Master Kenobi," Hett said. "That I promise." Hett's hands dropped to his belt and the two light-sabers practically leapt into his gloved hands. He ignited both weapons at once, unleashing their identical green energy beams.

He swung fast with the lightsaber in his right hand but Ben blocked it. The lightsabers sizzled loudly as they clashed. It was fortunate for Ben that he had continued his Jedi exercises on Tatooine, that he had not allowed his reflexes to become dull. He did not think about how long it had been since he had last used his lightsaber in combat. Nor did he consider that he was older than Hett by at least a decade, or Hett's considerable skills with his own weapons, and that the Tusken was far more experi-enced at fighting in the desert. Ben knew that any such thoughts would probably only get him killed. As prepared as Ben was for many things, he was not ready to die. Not yet. Not today.

Hett brought his other lightsaber in at a sharp angle, forcing Ben to lurch back. Ben gripped his own weapon with both hands as he swung at Hett's legs, but Hett blocked the swipe. There was another loud sizzle as the blades dragged across each other. Ben gasped as Hett launched a powerful kick to his midriff. The kick knocked Ben off his feet, and as he fell back through the air, Hett hurled one of his lightsabers at Ben's body. Ben clung tight to his own lightsaber as he twisted his body in midair to avoid being struck by the spinning blade of Hett's weapon. The moment Hett's lightsaber whipped past Ben's head, Hett used the Force to retrieve it, drawing it back to his waiting left hand. As Hett caught the lightsaber, Ben rolled up from the ground and swung out again. Hett blocked the strike with his right lightsaber, then threw his left arm forward to smash his other lightsaber's handle into Ben's jaw . Ben ignored the painful jolt to his head and reflex-ively brought his blade up high, forcing Hett to block the blow with his right lightsaber and leaving his own midsection briefly exposed. Before Hett could strike with his other lightsaber, Ben kicked him hard in the stomach. Hett grunted, but he didn't go down. He lashed out again at Ben, kicking up sand as he moved in for the kill. Not one of the mounted Tuskens so much as flinched as they watched the duel, nor did they rally for their chief. They merely watched in silence, waiting for the outcome. Ben blocked each blow, but he wasn't doing it with ease. Hett was far more experienced at fighting on the sand and in the desert heat. Ben knew that his opponent would never surrender, let alone withdraw. As much as he hoped to avoid killing Hett, he also knew that they couldn't keep fighting indefinitely.

But in the end, Ben knew he wasn't fighting for his own life. He was fighting for Luke's .

Quickly raising his left hand, Ben used the Force to push out at Hett, shoving him back through the air as Ben's lightsaber swept up and through Hett's right arm. Hett shouted as his arm fell away from his body. As Hett stumbled back, Ben used the Force to tear Hett's other lightsaber from his left hand's grip. Both of Hett's lightsabers deactivated as they sailed past Ben and landed in the sand behind him. Hett crumpled to his knees. His tribesmen watched as Ben stepped forward, leaned down to grip the top of Hett's facemask, and then pulled the mask off his head.

The fallen Jedi cradled the wounded stump of his right arm as he lifted his gaze to meet Ben's . Hett's unmasked face was that of a human, but covered with black, angular tattoos.

Now, let’s look at the fight in passages.

He swung fast with the lightsaber in his right hand but Ben blocked it. The lightsabers sizzled loudly as they clashed. It was fortunate for Ben that he had continued his Jedi exercises on Tatooine, that he had not allowed his reflexes to become dull. He did not think about how long it had been since he had last used his lightsaber in combat. Nor did he consider that he was older than Hett by at least a decade, or Hett's considerable skills with his own weapons, and that the Tusken was far more experienced at fighting in the desert. Ben knew that any such thoughts would probably only get him killed. As prepared as Ben was for many things, he was not ready to die. Not yet. Not today.

In the beginning, Kenobi and Hett fight evenly. As they duel, Kenobi notes that Hett has numerous advantages. He notes that despite continuing his Jedi exercises and practice with the Force, it has been two years since he used a lightsaber, which he believes has made him slightly rusty. He then comments on the terrain, noting that Hett has a distinct terrain advantage. However, Ben defends himself to the best of his ability, even with these disadvantages.

Hett brought his other lightsaber in at a sharp angle, forcing Ben to lurch back. Ben gripped his own weapon with both hands as he swung at Hett's legs, but Hett blocked the swipe. There was another loud sizzle as the blades dragged across each other. Ben gasped as Hett launched a powerful kick to his midriff. The kick knocked Ben off his feet, and as he fell back through the air, Hett hurled one of his lightsabers at Ben's body. Ben clung tight to his own lightsaber as he twisted his body in midair to avoid being struck by the spinning blade of Hett's weapon. The moment Hett's lightsaber whipped past Ben's head, Hett used the Force to retrieve it, drawing it back to his waiting left hand. As Hett caught the lightsaber, Ben rolled up from the ground and swung out again. Hett blocked the strike with his right lightsaber, then threw his left arm forward to smash his other lightsaber's handle into Ben's jaw

At first, Hett has a clear edge. He lands two successive hits on Kenobi, and drives him back. Kenobi is also forced to perform flips to avoid Hett’s saber throw, landing on his backside.

Ben ignored the painful jolt to his head and reflexively brought his blade up high, forcing Hett to block the blow with his right lightsaber and leaving his own midsection briefly exposed. Before Hett could strike with his other lightsaber, Ben kicked him hard in the stomach. Hett grunted, but he didn't go down. He lashed out again at Ben, kicking up sand as he moved in for the kill. Not one of the mounted Tuskens so much as flinched as they watched the duel, nor did they rally for their chief. They merely watched in silence, waiting for the outcome.

At this point, Ben appears to have fully shaken off any rust from his two years of not using a lightsaber. Like Hett before him, he lands a kick on Hett when he breaks through the Tusken’s defences. However, Hett recovers very quickly and re-engages.

Ben blocked each blow, but he wasn't doing it with ease. Hett was far more experienced at fighting on the sand and in the desert heat. Ben knew that his opponent would never surrender, let alone withdraw. As much as he hoped to avoid killing Hett, he also knew that they couldn't keep fighting indefinitely.

This is interesting. While it is true Ben notes that he doesn’t want to kill Hett, he also is struggling to block Hett’s blows, especially with the terrain advantage Hett enjoys. Ben clearly isn’t holding back, here. He might not want to kill Hett, but he also refuses to let him pass and knows that if he dies, Luke dies too. So far, the two have fought relatively evenly, and Ben muses that this could go on for quite some time.

But in the end, Ben knew he wasn't fighting for his own life. He was fighting for Luke's .

Quickly raising his left hand, Ben used the Force to push out at Hett, shoving him back through the air as Ben's lightsaber swept up and through Hett's right arm. Hett shouted as his arm fell away from his body. As Hett stumbled back, Ben used the Force to tear Hett's other lightsaber from his left hand's grip. Both of Hett's lightsabers deactivated as they sailed past Ben and landed in the sand behind him. Hett crumpled to his knees. His tribesmen watched as Ben stepped forward, leaned down to grip the top of Hett's facemask, and then pulled the mask off his head.

This is what I find very interesting. Until this point, neither Hett nor Ben had an obvious advantage over the other as they duel for several minutes. However, the moment Ben thinks of Luke, he’s suddenly able to move skillfully and fast enough to send Hett flying backwards with the Force, and then cut off his arm before Hett can recover and react.

In short, Obi-Wan lets go of his attachment and reservation to this man who was a former Jedi.

This might sound familiar:

With Anakin's grip on his wrists bending his arms near to breaking, forcing both their lightsabers down in a slow but unstoppable arc, Obi-Wan let go.

Of everything.

His hopes. His fears. His obligation to the Jedi, his promise to Qui-Gon, his failure with Anakin. And their lightsabers.

Startled, Anakin instinctively shifted his Force grip, releasing one wrist to reach for his blade; in that instant Obi-Wan twisted free of his other hand and with the Force caught up his own blade, reversing it along his forearm so that his swift parry of Anakin's thundering overhand not only blocked the strike but directed both blades to slice through the wall against which he stood. He slid Anakin's following thrust through the wall on the opposite side, guiding both blades again up and over his head in a circular sweep so that he could use the power of Anakin's next chop to drive himself backward through the wall, outside into the smoke and the falling cinders.

Anakin followed, constantly attacking; Obi-Wan again gave ground, retreating along a narrow balcony high above the black-sand shoreline of a lake of fire. Mustafar hummed with death behind his back, only a moment away, somewhere out there among the rivers of molten rock. Obi-Wan let Anakin drive him toward it.It was a place, he decided, they should reach together. Anakin forced him back and back, slamming his blade down with strength that seemed to flow from the volcano overhead. He spun and whirled and sliced razor-sharp shards of steel from the wall and shot them at Obi-Wan with the full heat of his fury. He slashed through a control panel along the walkway, and the ray shield that had held back the lava storm vanished.Fire rained around them. Obi-Wan backed to the end of the balcony; behind him was only a power conduit no thicker than his arm, connecting it to the main collection plant of the old lava mine, over a riverbed that flowed with white-hot molten stone. Obi-Wan stepped backward onto the conduit without hesitation, his balance flawless as he parried chop after chop.Anakin came on.Out on the tightrope of power conduit, their blades blurred even faster than before. They chopped and slashed and parried and blocked. Lava bombs thundered to the ground below, shedding drops of burning stone that scorched their robes. Smoke shrouded the planet's star, and now the only light came from the hell-glow of the lava below them and from their blades themselves. Flares of energy crackled and spat.

This was not Sith against Jedi. This was not light against dark or good against evil; it had nothing to do with duty or philosophy, religion or morals.

It was Anakin against Obi-Wan. Personally. Just the two of them, and the damage they had done to each other.

Obi-Wan backflipped from the conduit to a coupling nexus of the main collection plant; when Anakin flew in pursuit, Obi-Wan leapt again. They spun and whirled throughout its levels, up its stairs, and across its platforms; they battled out onto the collection panels over which the cascades of lava poured, and Obi-Wan, out on the edge of the collection panel, hunching under a curve of durasteel that splashed aside gouts of lava, deflecting Force blasts and countering strikes from this creature of rage that had been his best friend, suddenly comprehended an unexpect-edly profound truth.The man he faced was everything Obi-Wan had devoted his life to destroying: Murderer. Traitor. Fallen Jedi. Lord of the Sith. And here, and now, despite it all...Obi-Wan still loved him.

Yoda had said it, flat-out: Allow such attachments to pass out of one's life, a Jedi must, but Obi-Wan had never let himself understand. He had argued for Anakin, made excuses, covered for him again and again and again; all the while this attachment he denied even feeling had blinded him to the dark path his bestfriend walked.

Obi-Wan knew there was, in the end, only one answer for attachment…

He let it go

Kenobi’s strength is in his willpower. When he sets his mind to a task or transcends beyond material things like attachment and focuses on the greater good, he’s almost unstoppable. Whenever he’s faced a comparable opponent, he’s embraced who he is at his core and lets go of anything holding him back from being who he is. He’s as much a shelter in a hurricane as his opponent is the eye of the storm. When he did the above, he reach a level where he could even deflect blasts from MFV himself, who despite being mentally hindered had raw power beyond anyone else Obi-Wan have ever fought before:

Obi-Wan backflipped from the conduit to a coupling nexus of the main collection plant; when Anakin flew in pursuit, Obi-Wan leapt again. They spun and whirled throughout its levels, up its stairs, and across its platforms; they battled out onto the collection panels over which the cascades of lava poured, and Obi-Wan, out on the edge of the collection panel, hunching under a curve of durasteel that splashed aside gouts of lava, deflecting Force blasts and countering strikes from this creature of rage that had been his best friend,

His fight with Grievous further proves that, as after a pep talk from Mace that fundamentally changes his perspective on his fighting technique, he achieves what he was never able to before and definitively outduel Grievous:

Obi-Wan and Grievous often fought to a stalemate when they clashed, so evenly matched were they as warriors.

The Official Star Wars Fact File Relaunched #69

-

Mace Windu had almost smiled. "I created Vaapad to answer my weakness: it channels my own darkness into a weapon of the light. Master Yoda's Ataro is also an answer to weakness: the limitations of reach and mobility imposed by his stature and his age. But for you? What weakness does Soresu answer?"

Blinking, Obi-Wan had been forced to admit he'd never actually thought of it that way.

"That is so like you, Master Kenobi," the Korun Master had said, shaking his head. "I am called a great swordsman because I invented a lethal style; but who is greater, the creator of a killing form—or the master of the classic form?"

"I'm very flattered that you would consider me a master, but really—"

"Not a master. The master," Mace had said. "Be who you are, and Grievous will never defeat you."

So now, facing the tornado of annihilating energy that is Grievous's attack, Obi-Wan simply is who he is.The electrodrivers powering Grievous's mechanical arms let each of the four attack thrice in a single second; integrated by combat algorithms in the bio-droid's electronic network of peripheral processors, each of the twelve strikes per second came from a different angle with different speed and intensity, an unpredictably broken rhythm of slashes, chops, and stabs of which every single one could take Obi-Wan's life. Not one touched him.

After all, he had often walked unscathed through hornet-swarms of blasterfire, defended only by the Force's direction of his blade; countering twelve blows per second was only difficult, not impossible. His blade wove an intricate web of angles and curves, never truly fast but always just fast enough, each motion of his lightsaber subtly interfering with three or four or eight of the general's strikes, the rest sizzling past him, his precise, minimal shifts of weight and stance slipping them by centimeters

As we’ve seen time and time again, when Kenobi lets go of his attachments and embraces who he is at his core and not how others define him, he becomes virtually unstoppable.

His fight with Hett is very similar. Kenobi lets go of all attachments to Hett, to the Jedi, and focuses on one single, palpable concept: protecting Luke. He draws from it to push him to new heights, and it’s this that allows him to suddenly defeat Hett.

It’s not the only time Luke has boosted Kenobi far beyond his base abilities. I’m sure we’re all aware of this feat, where Kenobi moves so fast the very atoms that comprise his body begin to come apart:

The bloodwolf alone comprehends death.

And, therefore, the sweet pungency of life . howling his mournful wisdom, into the immeasurable night, to his estranged brethren the stars.

A bloodwolf is fearless. And though the Wise Prince will fight fang-and-claw to the death, maim and kill-

He also runs.

At a dead sprint, a bloodwolf, cub in jaws, can achieve velocities of eighty kilometers per hour.

On the Smuggler's Moon, a Jedi Master with his newborn Padawan ran faster.

Nar Shaddaa itself, circling the massive jewel of Nal Hutta, spins on its axis at a respectable one hundred and seventy kilometers per hour..

Obi-Wan Kenobi-ran faster.

And on a sand-lacerated mesa, a podracer utterly butchers distances at six hundred kilometers per hour.

Obi-Wan-

Ran-

Faster.

The Jedi Master ran over one hundred and sixty-five meters per second.

More than six hundred kilometers per hour.

No one, not Jedi, not Sith, had ever duplicated such superhuman locomotion.

Was Obi-Wan flying? He didn't know.

But he knew that, this time, he was not running from the blaster fire of destroyer droids. He was not running to save his own life.

He was not even running to save Qui-Gon from the slaying fire of Darth Maul's singing blade.

He was running ... to save the child he loved.

To call him a blur, a smear of speed, was to substitute poor poetry in favor of truth.

Space contracted-time distended.

Obi-Wan was a fulmination on reality.

Obi-Wan was Truth.

Obi-Wan literally blazed with kinetic light as he blistered through the Nar Shaddaan streets. And with every impossible angle he cornered, every slow-moving raindrop he dodged, every being he spared spontaneous combustion from contact with his supernatural momentum, the Jedi Master felt his muscles, his atoms, his very essence . rebelling into pandemonium.

Obi-Wan was-factually-flying apart.

Credit: Lone Wolf-A Tale of Obi Wan and Luke

In this feat, Obi-Wan moves over 600 km/hour, which calculates as 372 mph. If anyone’s curious, the fastest car in the world - the Bugatti Chiron Super Sport - moves at 304 mph at its peak.

This has become a pretty well known feat...but I don’t think the context is emphasised nearly enough:

But he knew that, this time, he was not running from the blaster fire of destroyer droids. He was not running to save his own life.

He was not even running to save Qui-Gon from the slaying fire of Darth Maul's singing blade.

He was running ... to save the child he loved.

What pushes Kenobi to move at over half the speed of sound isn’t his natural abilities. It isn’t attachments to the past, and it isn’t guilt or doubt.

It’s embracing the simplicity of the connection to Luke and his ongoing love for him that lets him surpass any other Jedi or Sith in history.

Obi-Wan is uniquely connected to Luke. Luke represents Obi-Wan’s hope for his future, a glimpse of what could have been and what might still be. He’s not Anakin, who he failed. He’s not Qui-Gon Jinn or the Order, who he lost. He’s not even his way of honouring the legacy of the Jedi, which he failed to do.

He’s the happy ending Kenobi craved, but could never realise.

Kenobi uses this love and hope as a sort of Force adrenaline, pushing him well beyond what his base self is capable of every time he calls upon him.

I’m sure you’re wondering by now why this is relevant. Well, interestingly enough, there’s this extract from the Life and Legend of Obi-Wan Kenobi, which goes into Obi-Wan’s thought process prior to confronting Vader and also during the fight:

Once the stormtroopers were gone, Ben emerged from the alcove and drew his lightsaber from his belt. He did not activate the blade but held it ready. He had a feeling he would be using his weapon sooner than later, and he had a feeling he would be using it against Vader. Ever since he had first sensed Vader's presence on the battle station, he had become increasingly certain that Vader knew he was on board. He had even allowed the possibility that Vader had let him deactivate the tractor beam, all in an effort to lure him into a trap. Ben had no fear of whatever Vader might have in store for him, but he still had to do everything in his power to make sure Luke would escape safely. If Ben failed that, he believed all his years on Tatooine would have been for nothing, and all would be lost.

-

With his peripheral vision, Obi-Wan saw the storm-troopers leave their stations beside the Falcon and run toward him and Vader. He continued his attack on Vader, and several exchanges later, he sensed Luke's movement and knew his plan had worked. He risked another glance into the hangar to see several figures racing for the Falcon's landing ramp: the droids, Chewbacca, Han Solo, Luke, and Leia! Obi-Wan hadn't known that Princess Leia was on the battle station, but he recognized the girl in the white dress from the hologram that R2-D2 had displayed. Obi-Wan did not believe in luck or coincidences, and seeing Luke unwittingly reunited with his twin sister, he knew that it was not a tractor beam that had brought him to the battle station, but the will of the Force. His fleeting glance also registered that Luke had paused behind his friends. Luke stood a short distance from the landing ramp and was staring straight at him, gaping.

Obi-Wan realized there was only one way Luke, Leia, and the others would escape the battle station alive. He smiled as he looked away from Luke, then closed his eyes and raised his lightsaber up before him.

Darth Vader did not hesitate to strike.

Once again, Kenobi has only one thought: protect Luke. Vader is a threat to everything Kenobi hopes for, including Luke’s survival. Ben has transcended his desire to survive. He’s abandoned any former attachments to Vader and now he is fighting to kill, with only one desire fuelling him and pushing him to give everything he has to kill Vader: protect Luke Skywalker. During this, Ben also acknowledges that there’s no other way that the Falcon will escape the ship, unless he tricks Vader by getting him to strike him down, thereby giving Luke and the others the time they need to board the Falcon and escape.

I don’t think it’s outside the realm of possibility that like with Hett, his feat on Nar Shaddaa, and his fights with Anakin and Grievous, Kenobi has once more transcended all attachments and the negative emotions they bring, and instead focuses on the present and the future. Just as the dark side is the average Force user’s “Force LSD”, clearing himself of all attachments and focusing on one thing (simplicity, letting go of the past, or Luke) is Kenobi’s. While by this point Ben’s aged body from the harsh conditions of Tatooine and his diminished (though still formidable) lightsaber skill have considerably limited the extent of this amp, it has still pushed him considerably beyond his base levels, allowing him to briefly stand toe to toe with Vader.

Part III - D Vader Post ANH

After Vader defeated Ben Kenobi, he felt more powerful than ever

From a distance, he heard someone scream “Nooo!”—a cry of utter despair. But Vader paid it no heed. The dark side surged within him as powerfully as he had ever felt it—for an instant. But then it stopped.

--Death Star

The surge of power stopped when Vader realized Ben has disappeared, and then his PTSD again stroke him down. but we have numerous statements that Vader returned after the explosion of the Death Star far more powerful.

When the Death Star battle station exploded into a thousand shards of light, it was thought that the threat of Darth Vader was lost to the endless void. But Vader survived. He returned from his unwanted sojourn into deep space even stronger, more powerful than he was before.

--Galaxy Guide 3

The more powerful figures may often be defeated but not slain. They may flee, like Darth Vader after the destruction of the Death Star, to return more powerful on another day.

--Gamer 5

This is because Vader after the defeat of Ben went through a surge of power because of his now bottomless rage:

Gallery

It is stated that Vader as of the events of Empire Strikes Back is Downright far more powerful then he was as of the events of a New Hope

“Within the armoed forces Vader now holds absolute power over the higher Imperial officers who scorned him earlier in his career. This situation reflects Vader's greater mastery over himself and over the Force in the time since the Battle of Yavin, an improvement that is readily apparent in his lightsaber style during the duel with Luke Skywalker on Bespin. Vader has largely freed himself of pain through the Force in the years since the Battle of Yavin and, by practice with living opponents both willing and unwilling, he has advanced his lightsaber technique. Baron Orman Tagge serves as testament to Vader's technique by this era, precisely blinded in both eyes by Vader's blade in a duel. Vader is thus a far more formidable foe on Bespin than he was against Ben Kenobi on the Death Star.”

-- Insider #62

Vader as of a New Hope is likened to an old cripple while Vader as of Empire Strikes Back is likened to the best swordsmen in England , which is quite..... large gap and growth.

"and so I accepted that it was a half-man, half-machine. But Jedi are meant to be quite agile. So for the next one, we got a really good swordsmaster in, the best in England. And Mark is a really good swordsman"

- George Lucas

It should be noted that this kind of growth, at this stage of his life which he should see far diminishing returns, shows how monstrously he has been growing since ROTS.

Part IV - Luke Skywalker- A - Power Of A Skywalker

Luke Skywalker, is the Jedi's only hope to defeat Darth Vader, whose death is Empesized by George Lucas, Yoda, and Obi-Wan over Darth Sidious, he is the only one powerful enough to do it:

it's a little nefarious because they think he's the only one who probably has the power to kill Vader. Their agenda is to kill Vader and basically cut off the Emperor's right hand.

--Geroge Lucas

He knows that, eventually, Darth Vader is going to come looking for them. He knows this whole thing is going to blow up into a big war. He knows a confrontation is brewing between Luke and his father. Ben hopes Luke will either save his father or kill him because whatever extra powers Luke's got in his lineage, he is the one person, who can probably fight his father and win.

--Geroge Lucas

But why is Vader emphasized over Sidious? more on that in the final part of the blog.

The focus part for now is, how much exactly is Luke powerful in comparison to other Jedi that he can challenge Vader? well Vader himself makes a rather direct comparrison:

“Not … possible!” Vader muttered, feeling his energy drain. “Such power … in a child. Not possible!”

-- The Rise and Fall of Darth Vader

Vader said those words in a confrontation with Luke, two years after ANH where Luke blocked his amplified power giving Vader a sense of how much exactly the young boy possesses raw, yet to be mastered, power.

The words, in a child, are a reference to Luke's young age which Vader knows exactly how much that is:

According to municipal records obtained from the settlement of Anchorhead on Tatooine, that was the name on the registration for a T-16 skyhopper owned by a human male pilot who had lived at the Lars homestead and was approximately nineteen standard years old.

Luke Skywalker.

So a 21-year-old Luke possesses such power impossible for his age, while Vader knows another 21-year-old very well, Anakin Skywalker at operation Knightfall.

This comparison becomes even more valid when we see that Luke is stated capable of killing the Emperor by Vader, Yoda, and Darth Sidious himself and C-Canon sources if he becomes a Jedi:

“What is thy bidding, my master?” “There is a great disturbance in the Force.” “I have felt it.” “We have a new enemy. The young Rebel who destroyed the Death Star. I have no doubt this boy is the offspring of Anakin Skywalker.” “How is that possible?” “Search your feelings, Lord Vader. You will know it to be true. He could destroy us.” “He's just a boy. Obi-Wan can no longer help him.” “The Force is strong with him. The son of Skywalker must not become a Jedi.” -Darth Vader and --

Emperor Palpatine, the Empire Strikes Back

Only a fully trained Jedi Knight with the Force as his ally, will conquer Vader and his Emperor. If you end your training now - if you choose the quick and easy path as Vader did - you will become an agent of evil.”

-Yoda, The Empire Strikes Back

Vader stepped to the railing and tried to collect his thoughts. I must obey my Master. I must deliver Luke to him. But if Luke can kill the Emperor, perhaps perhaps then I will be free.

-Vader, Return Of The Jedi

Gallery

power was that he had embraced the dark side of the Force. It was through the Force that Palpatine knew that Luke Skywalker could become a powerful Jedi and threaten his evil rule.

And The Emperor is not overestimating Luke, as confirmed by Vader:

“Perhaps you are not as powerful as the Emperor thought… impressive, most impressive.”

-Darth Vader, the Empire Strikes Back

and by the time of Return of The Jedi, Luke has become a Jedi knight.

Luke Skywalker

Luke Skywalker is a Jedi Knight. Since the death of his mentor, Obi-Wan Kenobi, and of his father, Anakin Skywalker, he is the last of the Jedi. He

Luke became a knight quote II

When Darth Vader first defeated Luke, the young man still had much to learn about the ways of a Jedi Here see him confident and sure of his powers as he faces Jabba the Hutt's men. Luke has become a the Jedi Knight

But you may ask, why did Luke crumble at the hands of the Emperor via Force Lightning? because Force Lightning is consistently shown to beat equals and even superiors.

Mace Windu with a Lightsaber is barely able to keep Lightning from Sidious , the same Sidious he just bested

Dooku defeats Yoda in combat by shocking him with Lightning, even though Yoda is more powerful

Gallery

luke was cut off from the force and such due to Palpatine's Lightning, explaining why Luke didn't he TK his Lightsaber out and use the Lightsaber to block the Lightning from Palpatine

Yoda had told Luke that electrical shocks, applied at different intensities and at irregular but frequent intervals, would prevent a Jedi from concentrating, from channeling the Force. They could render a Jedi helpless.

But Yoda had never told Luke that emotional shocks could do the same thing.

They could. And just as no amount of self-control would allow a Jedi to ignore the effects of electrical shocks on his body, neither could self-control keep Luke safely out of his memories

--Legacy of the Force – Fury

even Grandmaster Luke who is way above the Hidden one was having trouble Deflecting the Hidden One's Lightning, this shows Lightning is hazardous for people who are way above, let alone people who are below

It happened all at once: the Hidden One gesturing toward Luke, Ben leaping away, lightning flashing from the Hidden One's hands. It was not the purplish lightning of Emperor Palpatine, which had so nearly cost Luke his life nearly forty years before; it was all brilliant whiteness.Luke had his lightsaber activated and up in time. The lightning crackled against his glowing blade. The strength behind the attack, of the Hidden One's energy and anger, took Luke off his feet and threw him backward. He slammed into a pillar, feeling jolts of pain in his spine and the back of his head.But the lightning did not reach him. His blade kept it at bay. And, bracing himself with the Force, Luke took a step forward.

--Fate of The Jedi

Palpatine was using full power, there is no suggestion he was using anything less

When the evil Emperor, Supreme Master of the Dark Side of the Force, turned the fullness of his malevolence against Luke, Anakin Skywalker suddenly awoke from the curse that had imprisoned him for so long… Shedding his bleak and soulless identity of Darth Vader, Anakin took the full force of his Dark Master’s evil lightning upon himself - and hurled the Emperor to his death.

-- Dark Empire 1 Endnotes

And then there is the rather popular statement that the Emperor can one-shot Luke by raising his hand:

In this final revision to the duel, Lucas worked out in his mind the emotional mechanics of the script, as Luke, Vader, and the Emperor stage their "Mexican standoff": "The core of all this thing is [that] the Emperor is the master and Vader is the apprentice," Lucas would explain. "He knows that if he gets into a lazer fight with the Emperor, he won't win. He knows his son can't win. Neither one of them can beat the Emperor. Together they might. In the first sequel, he reveals that when he says, 'Together we can rule the universe.' That's still his plot in Jedi. It's just that his son has said, ‘No, I'm not going to do that.' So that's a bit of a problem.

.

the Emperor, 'When he starts to strike me, you're going to have to take him out.' If Vader doesn't block Luke's lazer sword, the Emperor could just raise his hand and that would be the end of it.

There are a couple of points that are missed by people abusing this, for one this is Vader's POV "He knows" section, something not as reliable as you may think which I will address at the end, but he still thinks he and his son can beat him, someone who he thinks has Godlike powers, not much of a one-shot at all.

Secondly, The Emperor has been toying with Luke, and when he starts to strike the Emperor, is when he will strike.

"Take your Jedi weapon. Use it. I am unarmed. Strike me down with it."

-The Emperor to Luke, Return of the Jedi

That's the toying which is referred to, now what does Yoda tell Luke at the beginning of the movie?

"Do not underestimate the powers of the Emperor... or suffer your father's fate you will."

-Yoda to Luke, Return of the Jedi

In Return of the Jedi, why does Luke throw away his lightsaber after he defeats Darth Vader? When he did this, he was unarmed and couldn't defend himself from the Emperor's Sith lightning.

There's no reason to believe that Luke knew the Emperor could hurl lightning. We don't know whether Yoda elaborated upon his warning not to underestimate the powers of the Emperor. Regardless of whether Luke knew or not, his casting away of his weapon had nothing to do with tactics or strategy, and had everything to do with making a point. His gesture showed Palpatine that he could throw away his aggression, and thus, that the Emperor would not be able to use that approach to lure him to the dark side as he did Anakin.

-Insider 73

Luke doesn't know about lightning or how to defend against it, Sidious is trying to make Luke underestimate him as a threat, George notes he is doing this, and Pablo applies Yoda's warning to confronting Sheev in general, what would end isn't Luke but Emperor's toying and Manipulation.

Luke Skywalker is the bloodline of the force, is scaled and stated numerous times to be able to beat people who dwarf past force users in power, and now he is a full Jedi knight in control of his power and ready to battle the duel which will change the fate of the universe

Part IV - B - The ROTJ Duel

Luke Skywalker went to battle with Vader and his Emperor, Yoda was confident enough in Luke's abilities that he finally let himself pass:

It seemed to Luke that the Jedi Master chose the moment of his passing. It was as if Yoda had completed the last of his great tasks for the galaxy and now he was allowing nature to take its course. It was entirely possible, Luke thought, that Yoda had kept himself alive for all these years through his own personal power, refusing to perish until he finished training the last Jedi.

-

Becoming sick after the departure of Luke Skywalker from Dagobah, Yoda had clung to life in order to finish his apprentice’s Jedi training.

-

Yoda had been ill for some time before he died. He had held onto life because he knew that Luke would return to Dagobah. Yoda stayed alive long enough to tell Luke that he had learned everything he needed.

Luke is ready to face Vader and Sidious, even George Lucas and C-Canon approve of this by saying that Vader and Luke can beat Darth Sidious:

He knows that if he gets into a laser fight with the Emperor, he won't win. He knows his son can't win. Neither one of them can beat the Emperor. Together they might. In the first sequel, he reveals that when he says, 'Together we can rule the universe.'

--George Lucas

However if Vader and Luke -father and son- were to combine their might against the Emperor, they could usurp Palpatine's power and bring a new era of peace to the galaxy.

-- Shadows Of The Empire Sourcebook

now how two vs two works in star wars , both sides must be relative in term of power for the Two vs two to actually work properly

people often cite this fight as evidence that Maul >> Qui Gon and Obi Wan individually

now you may believe this is very simple as Maul was fighting both at once , he would absolute dominate one

but thats sadly not how Star Wars work , not only is Maul >>> Qui Gon contradicted by

but let's look at some more 2v1 Duels in Star Wars , lets take a look at Season IV of Clone Wars

Maul and Savage being dealt at once by Kenobi , now does this mean he can absolutely dominate one at a time ? No , but lets look at something that is even more damning

now lets look at some facts

and Let's make it clear, he was enough of a match for Both Anakin and Obi-Wan , at once at that

he was a " Formidable opponent " for them

Infiltrating General Grievous' flagship, the Jedi found the Chancellor bound to a chair in the spacious observation deck. Waiting for them was Count Dooku. Obi-Wan and Anakin challenged the Sith Lord as a team. Dooku proved a formidable opponent.

Source: http://www.starwars.com/databank/obi-wan-kenobi-biography-gallery

this again Reiterates that Dooku was a formidable opponent for Both of Them z at once .

Waiting for them was Count Dooku, and unlike the impulsive and disorganized attack that had marked their last confrontation with Dooku, Obi-Wan and Anakin challenged Dooku as a team. Dooku proved a formidable opponent. He Force-pushed Obi-Wan with terrible strength, tossing the Jedi Master like a rag doll against the walls of the quarters. Kenobi was knocked unconscious.

Source: The Complete Star Wars Encyclopedia

The Junior Novelization of Revenge of The Sith suggests Dookh was at ease , while flighting both Obi Wan and Anakin and he was so Good during the Duel that he made them Desperate to the point they started jumping styles and throwing baits in other words, he made them Very desperate

Count Dooku deserved his reputation as a master of the old style of lightsaber fencing. Even with both Anakin and Obi-Wan pressing him, he seemed at ease. The Jedi used every trick they knew, leaping and striking from unexpected directions. Dooku blocked them all.

Source: Revenge of the Sith Junior Novelization

so Dooku ~ Revenge Of The Sith Duo

so by this logic, he should be significantly more powerful than Anakin and Obi-Wan individually......well........... except he is not, Dooku is stated to be Equal to Anakin........

All of the super battle droids had been cut down; only Anakin and Dooku were left. Down the long length of the room they fought, neither one able to gain an advantage.

Source: Revenge of the Sith Junior Novelization

so now we can conclude that

in Star Wars, Duos don't always give you automatic Linear 1+1=2 type scaling, Logically the Jedi Duo of Revenge Of The Sith should be twice as strong as Dooku but Dooku still outmaneuvered them because Obi-Wan was too weak for Dooku, both parties must be relative for Star wars 2v1s to work

So both Vader and Luke are at the very least comparable to Darth Sidious as of ROTJ to be able to defeat him.

While Vader's performance is massively hindered by his conflict and even his PTSD because of the familiar past event mimicking the present:

"As you wish," said Vader. He had not forgotten how Anakin Skywalker had obeyed Palpatine's command to kill Count Dooku, and had no reason to doubt that the Emperor had already planned a test for Luke to determine whether Vader would remain his apprentice.

Using the Force, Luke snatched up his weapon, activated its blade, and swung fast at the Emperor's head. But Vader moved faster, activating his own lightsaber to deftly block Luke's attack. The sight of Vader and Luke crossing lightsabers excited and amused the Emperor, and he cackled with perverse glee. Vader recalled that Palpatine had laughed the same way over two decades ago, when he had ordered Anakin Skywalker to kill Count Dooku.

--The Rise And Fall Of Darth Vader

And his Son being amplified by Rage:

Link

As their duel carried on throughout the throne room, the Dark Lord sensed that Luke was drawing from his own anger to fuel his attack. From his throne, the Emperor said, “Good. Use your aggressive feelings, boy! Let the hate flow through you.”

--The Rise And Fall Of Darth Vader

Vader fought with his Son as equals until the Darkside amp and Vader's hindrance were too much and Luke became the victor.

Part V -Darth Vader Vs. Darth Sidious- A - Battle Of Equals

Throughout the blog, I established many things that make Vader and Sidious comparable. be it Ben Kenobi who was a threat to both of them and conceptually on par with Sidious with numerous combative supremacy statements he and Vader had over the Emperor, Luke Skywalker who Vader is at least equal to is narratively the one able to beat Sidious, or that George Lucas himself with his approved C-Canon showed that Vader is the end goal and his death is emphasized over Sidious and it will cut off his right hand.

But there is more:

Darth Vader is the ultimate villain of the Star Wars universe, the malevolent Dark Lord of the Sith.

-Star Wars Poster Monthly 1

“Darth Vader is the preeminent lightsaber master in the galaxy, now that Obi-Wan Kenobi has been destroyed.”

- Star Wars Lightsaber Dueling Pack - Darth Vader.

You fight with Vader, but there is no way that you can beat him. He is second only to the Emperor in power. As a warrior, he is second to none. You have no chance.

-Star Wars: Return of the Jedi: Decide Your Destiny

Together with an old Jedi Master, a cocksure pirate, a lovely princess, and an eclectic group of Rebels, Luke fights against the ominous Empire and its greatest warrior, Darth Vader.

-Star Wars: Skybox: Collectible Sticker and Story Album

The Force will be with you when you collect these beautiful vinyl figures of Rebel heroes and their greatest adversary, Darth Vader.

-Star Wars Insider Magazine #23

Vader and Sidious were always close to each other, with Vader being the supreme combatant of the two in the Emperor's elder years making them as formidable as each other in ESB:

Once Supreme Chancellor Palpatine, the black-cloaked Darth Sidious has fulfilled his masterful plan and taken control of the entire galaxy, with the equally formidable Dark Lord of the Sith by his side.

-- Galactic Files: Emperor Palpatine

Vader and Sidious's growth mirrors each other, they were close to each other in ANH via Ben Kenobi, They are directly stated as equals in ESB, and they are again on par with each other Via Luke scaling.

Sidious TPing Vader from across the galaxy is always used to lower him in front of his master, while its completely not power related

Vader was brought down while he was in his shuttle and privately musing about Luke, he wasn't combat-ready at all. And for the record, Luke also did something similar shortly after ANH, and that was in the middle of a space battle, a scenario where Vader would no doubt be far more combat-ready, yet we all agree he is far above this iteration of Luke:

Thus, that doesn't prove anything in terms of Vader's power relationship with the Emperor. If Vader's mind was "unprotected" during a space battle, I don't see why it wouldn't be while he is in his shuttle musing about Luke.

Then we have Vader killing his Master while weaker than ever before, tanking his full potent lightning, and only dying as a result of being a light sider with no more life-sustaining suit.

the novel itself clearly states the lightning was "tearing into" Vader, so even if the lightning was initially hitting in all directions Vader still took the full brunt of it.

And for the record, the Emperor himself acknowledged Vader as powerful enough to kill him

Yes, Vader remained strong in the Force, but strong enough to succeed me? Never. Granted, he was strong enough to kill me. But that only lasted for so long.

-- Jedi vs. Sith: The Essential Guide To The Force

Vader's weaknesses are outright stated more than once to show the condition he is in,

Although it would not have seemed possible, the outpouring of bolts from the Emperor's fingers actually increases in intensity, the sound screaming through the room. Luke's body writhes in pain. Vader grabs the Emperor from behind, fighting for control of the robed figure despite the Dark Lord's weakened body and gravely weakened arm.

-- Return Of The Jedi Movie Script

As the Emperor continued to strike Luke with his barrage of Sith lightning, Vader struggled to his feet. One leg was broken, and the other wasn't working right.Moving awkwardly, he shifted his bulk to stand beside his Master. On the floor, Luke writhed in agony, and was on the verge of death as he groaned, "Father, please. Help me."

It took all of his remaining strength to seize the Emperor from behind, lift him off his feet, and carry him to the open elevator shaft. The wretched Emperor continued to release lightning bolts, but they veered away from Luke and arced back to crash down upon him and his insurgent apprentice. The lightning penetrated Vader's life-support suit and electrified Anakin's organic remains, but he lurched forward until he could throw the Emperor into the elevator shaft.

Palpatine screamed as his body plummeted down the shaft. Still trapped within Darth Vader's armor, Anakin collapsed at the shaft's edge, but heard the explosion of dark energy that consumed the falling Emperor.

-- The Rise And Fall Of Darth Vader

Yet the Emperor still physically struggled against him:

Palpatine struggled in the grip of Vader's unfeeling embrace, his hands still shooting bolts of malign energy out in all directions. In his wild flailing, the lightning ripped across the room, tearing into Vader. The Dark Lord fell again, electric currents crackling down his helmet, over his cape, into his heart. Vader stumbled with his load to the middle of the bridge over the black chasm leading to the power core. He held the wailing despot high over his head, and with a final spasm of strength, hurled him into the abyss.

-- Return Of The Jedi

But people mostly disregard this magnificent feat for this statement:

“So Vader is not powerful enough to kill the Emperor, but he does so in a very unexpected way. He does it not out of thinking or fear. He does it out of the super energy of wanting to protect his son, out of compassion. Vader finally has compassion for his son and realizes that his life has been a sham.”

GL saying that Vader isn't powerful enough to kill Sidious is a present statement referring to Vader's current condition.

Vader being amped by the power of love in this horrible state can only bring him back to normal levels, seeing as the amp was not even significant enough for the oness to be shown as a shine of light.

But then why does Vader take orders? Why does Vader see Sidious as someone he can never wish to beat? Isn't he equal to him or even better combatively?

Well, I am going to give an answer to that.

Part V - B - Force Lightning

I've already mentioned and proven how Force Lightning can turn the tides in a battle of equals or even slight superiors, in case Vader his inability to conjure it is one of the main reasons he can't take Sidious head-on:

Unfortunately, because of his artificial arms, he was unable to conjure Sith Lightning or be invulnerable to it. He would always be weaker than the Emperor.

--The Rise And Fall Of Darth Vader

Not only he was unable to use them, but he was also very vulnerable to them:

Sidious lifted his arms, hands deployed like claws, as if to summon and hurl Sith lightning. “Because you know that I could easily overwhelm the delicate electrical systems of your suit.”

--Dark Lord Rise Of Darth Vader

As you can see, it has been mentioned over and over again is the main reason Vader will always be weaker than the Emperor, and a fight between them would at best be a huge gamble.

And this is not the only time someone equal or even more powerful than Sidious was his henchman and didn't rebel against him:

"The mission begins at the end of the story of The Force Unleashed and re-imagines the Star Wars Saga as if the Secret Apprentice had killed Darth Vader and taken his place at the Emperor's side, becoming the most powerful Sith Lord in the universe." https://web.archive.org/web/20091212115534/http://www.starwars.com/games/videogames/news20090827/index.html "The mission begins at the end of the story of The Force Unleashed and re-imagines the Star Wars Saga as if the Secret Apprentice had killed Darth Vader and taken his place at the Emperor's side, becoming the most powerful Sith Lord in the universe." https://web.archive.org/web/20120501084728/http://www.lucasarts.com/company/release/news20090724.html

Lord Starkiller was also superior to the Emperor but didn't rebel against him, with Sidious being so sure of this by taunting him and telling him he is just a placeholder.

So either Starkiller's damaged cyborg body was why he took orders or the next reason Vader views defeating Sidious as an unclimbable mountain.

Part V - C - A Master Maniuplator

He does it not out of thinking or fear

It was always Vader's end goal to kill his Master, his passion his desire to live was to someday taste the power of being the superior again and at first, he completely believed he would:

He had no doubt that the Emperor knew what he wanted more than anything: the power to kill his Master.

--The Rise And Fall Of Darth Vader

There would come a day, however, when they would be equals.

--Dark Lord Rise Of Darth Vader

So how did Vader go from this, to this:

Vader stepped to the railing and tried to collect his thoughts. I must obey my Master. I must deliver Luke to him.

So he must obey his more powerful Master, but

But if Luke can kill the Emperor, perhaps perhaps then I will be free.

His inferior or equal can kill Sidious?

Vader's view of Sidious is not remotely reliable as he views Sidious as someone who is way above blowing entire solar systems

Luke Skywalker, the man, is adept at all the principal powers and practices of a Jedi...and he stands at the threshold of awakening to the legendary powers of the great Masters of old...

But, as we shall see, others, committed to the path of the Dark Side, are also gaining access to powerful secrets... Luke is not alone in his quest for Mastery.

As Luke's father once said, during the time when he served the greatest known wielder of the Dark Side of the Force, the Emperor: "The ability to destroy a planet-or even a whole system-is insignificant next to the power of the Force."

Go carefully, Luke. You have won much...but the war is not yet over. Go carefully, and remember-the Force will be with you...always.

If we go even deeper we realize Vader has overrated Palpatine to the point he views Palpatine as an omniscient god of some sorts

to Imperial soldiers on Endor and is brought before his father. Because this reunion was anticipated by the Emperor, who has also foreseen that his Sith apprentice will deliver Luke to him, Vader realizes his own destiny is simply to be a pawn in his Master's schemes. Faced with his Master's apparent omniscience, Vader abandons his ambition to overthrow Palpatine and rule the galaxy side-by-side with his son, and Luke notices that his father is less bold than he was at their last meeting on Cloud City. Sensing Vader's conflict, Luke's

he overrates the Emperor because Vader is under the complete grip of Sidious, making Vader overrate the most powerful practitioner of the Darkside

The Emperor was expecting us, but first I had to try to persuade my father that Anakin Skywalker still existed, somewhere deep inside. I was certain that there was still good in him, I could not believe that the Emperor had fully driven it from him. For a moment he seemed to listen. I thought that I was reaching him. He looked at my lightsaber and acknowledged that I had become powerful. I could feel the conflict within him-he was thinking of times long ago, he was thinking of Obi-Wan Kenobi. But then the power of the dark side seemed to tell him that it was too late, and he signalled to some stormtroopers. We were going to meet the Emperor, and it seemed to me in that bleak moment that my father was truly dead.

Luke gave in to his destiny. He surrendered to Darth Vader, and met his father face-to-face for the second time. He tried to reach Anakin Skywalker, asking him to let go of his hatred. Darth Vader doubted himself for the first time in years. But the Emperor's hold on him was deep and Luke could not break through.

due to Luke, Vader finally learns how to resist The control Sidious had over him

AN APPRENTICE'S REBELLION

I could feel the conflict within him he was thinking of times long ago he was thinking of Obi-Wan Kenobi but then the power of the Darkside seemed to tell him that it was too late.

-Star Wars Annual 2012

When Sidious tried with all his power to turn Luke and failed:

this was the first time Vader realized Palpatine is not an immovable object and that he can be destroyed somehow

ATTACK OF THE SITH Angered by Luke's unwillingness to follow his father's path, the Emperor releases a storm of Sith lightning on the Jedi. But in failing to foresee Luke's defiance, the Emperor reveals that his own powers are fallible, and a wounded Vader realizes Palpatine can be destroyed.

and when Finally Vader learns to resist Palpatine's mental and psychological grips on him, Vader realizes how easy the choice has been, forever , how he was able to end the Psychological control and Physically overpower Sidious

Suddenly, he made a decision. Vader hefted Palpatine and held him high over his head. Part of him wondered what he was doing, while part marveled at how easy his choice had been. Vader strained toward the core shaft, while the Emperor's dark side electricity arced back and struck him on the head and torso, roasting his remaining bodyparts

meaning all Palpatine > Vader things from Vader's perspective are a result of Psychological Manipulation and such, not real power .

it's not uncommon for people to fear equals or even inferior, for example, Palpatine himself feared dying Darth Plagueis's power

Seen through the Force, he was a nuclear oval of mottled light, a rotating orb of terrifying energy. If the Maladian attack had weakened him physically, it had also helped to shape his etheric body into a vessel sufficiently strong to contain the full power of the dark side.

Darth Plagueis

Same Palpatine is stated to be the most powerful Sith lord and capable of killing Plagueis,

Sidious paused, then, in derision, added, “Plagueis the Wise, who in his time truly was, except at the end, trusting that the Rule of Two had been superseded, and failed to realize that he would not be excused from it. Plagueis the Wise, who forged the most powerful Sith Lord the galaxy has ever known, and yet who forgot to leave a place for himself; whose pride never allowed him to question that he would no longer be needed.”

In truth, Palpatine was well versed in the ways of the Force, having been apprentice to Darth Plagueis the Wise, a Sith Lord who was a master of arcane and unnatural knowledge. In true Sith tradition, Palpatine murdered his Master upon receiving the skill and ability to do so.

Source: The Complete Star Wars Encyclopedia

Sidious served for many decades as the apprentice of Darth Plagueis, learning diligently at the feet of his Master. Once he possessed all of Plagueis' secrets, he retired him.

Source: Insider #88: Heritage of the Sith

While always taught he was the true Master of Life and Death, a God, it's no coincidence that he tried the same manipulation to show himself as an Entity to Vader, he was always sure of his loyalty despite the risks he possesses

He collected some of these Force adepts and took them to his citadel on Byss, where he initiated them in the powers of the dark side. All of those he taught, human or alien, was only taught enough to fulfill Palpatine's wishes. He didn't want any of them rising up against him. Bad enough that Vader was as powerful as he was, though Palpatine was certain of Vader’s loyalty to the dark side.

-- The Essential Guide To Characters

Sidious rules by fear and with that he controls his servants, he never wanted a successor but he still took Anakin as an apprentice someone established more powerful than him, he wanted Luke as an apprentice someone with far more potential, He knows he can control them and use them forever never needing to give up his throne:

The Emperor was the architect of all the pain and suffering that the clone wars inflicted. he rules by fear.

-Star Wars Activity Annual

So Vader's statements on Sidious can never be taken as facts, and the two being equals and Vader being the more threatening of the two in combat is something that is mentioned everywhere.