The Godkiller is a mystical blade forged of Olympus through the godly element known as Eighth Metal. It has a solid gold sheen and crackles with primordial energy when in the hands of a weaponer. Normally taking the appearance of a sword, it has the ability to change and morph its shape on the users command.
Created by the God of the Forge to honor a final will and testament of his late brother. Hephaestus crafted a mighty blade within his quarry in order to honor that deal at a later date, when time came to honor the fallen god's last request. He would offer the battlement, along with an extravagant sum in gold, to the worlds deadliest assassin in return for the disposal of an ancient evil.
The Greek Titan Lapetus was the mark said haughty former king of Olympus wished terminated, failing that he would prefer the eternal enemy of the gods to have destroyed his old kingdom and everyone in it. Not wishing his family to've outlived him or his rule as their leader.
As Slade is a mere mortal with some moderate enhancements, the Deathstroke was gifted with a weapon of the gods to enable the battle and besting of a god. For it was designed and crafted by the forge deity for that specific purpose, as was the prerogative of Apollo's contract. Once on the island of the Amazons, where the remains of the slumbering titan lay across their land, a chain of events lead to the release of the baleful old god and his armies whom immediately begin slaughtering his watchers.
Deathstroke would fight his way across Themyscira both through friend and foe alike while being guided by the divine arsenal in a box, all the while learning what else the weapon could do with time and practice. Both heroes Wonder Woman and Superman did battle with various disasters.
Slade would fulfill his contract with the god who deceived him into unleashing hell on earth. While in heated battle with the tyrannical divine entity, the sword would cross with Lapetus's spear which contained the soul of his sibling titan within it. Exploiting this weakness to enrage the hateful immortal, Deathstroke shattered his companions essence when he cleaved his weapon in two.
Sending the mad numen into a blind frenzy in which Wilson used as the opportunity to cleave his heart using the very weapon forged to kill him and his kind. The contract completed, Hephaestus appeared before everyone present to award his assassin for his efforts while taking back his creation.
In a different reality within the Dark Multiverse, the downed and weakened batman of Universe -12 would eventually take on the weapons and other affiliated wears of the gods out of revenge against an emboldened Ares who would wage war on the whole earth. After killing the war god and the rest of the Olympians along with their acolytes the arms of Haphestus eventually fell into his hands, including the Godkiller sword which he would make use of in his deicide of the Grecian Pantheon and in later life while in the service of Barbatos as one of his Dark Knights.
God Killer bears various divine qualities primarily for the purpose of slaying the almighty. The munition seemingly possesses an awareness which both influences and seeks to overtake the users own consciousness to a subtle extent. Capable of altering its physical form becoming a sword or blade pair, a form of binding mantecle, a bo staff, whip or simply reforming after it is shattered. Discharging a form of eldritch or metaphysical energy as concussive force or shockwaves with every strike, capable of disorineting even a fully powered Kryptonian. And has the capacity to physically or mentally augment the wielder to the degree they can battle and best godly or godlike opponents in battle. E.I giving them bolstered intuitive perception to ascertaining spiritual sight and sense an adversary's weaknesses to simply guiding ones aim in order to find that which its user seeks.