Best swordfighter in fictional history.

I think The Turtles have totally won.

Palpatine

Sasaki Kojiro. A deaf and mute swordsman with unfathomable skill. I doubt few if any of these guys can nonchalantly defeat a master swordsman that's highly regarded as one of the best in the kingdom with nothing but a simple twig.

Another would be Rain. He wields a blue demonic sword and if there ever was a word to describe one that far outclasses a Master, Rain would hold that title. A true prodigy of the sword. Not only that, he's a master tactician and strategist and a genius in the field of magic. He is the embodiment of the word, overpowered lol