Every few years, Marvel tends to introduce a new cosmic hero or villain who's billed as the most powerful character in the universe. However, Marvel tends to be more reserved when it comes to all-powerful weapons. For decades. the Infinity Gems' combination within the Infinity Gauntlet that took the position of "most powerful weapon," but that might just be changing with the All-Black Necrosword.
While the Infinity Stones have been playing a less prominent role in the wake of their widespread use in stories that culminated in Avengers: Endgame and Infinity Wars, All-Black the Necrosword has been popping up in some surprisng corners of the Marvel Universe over the past several years, and it still is to this day.
Although it was originally introduced in Jason Aaron and Esad Ribic's Thor: God of Thunder #2, All-Black the Necrosword's true origin was revealed in Donny Cates and Ryan Stegman's Venom #4. Created by the symbiote god Knull and forged with the blood of a Celestial space god, the symbiotic All-Black earned its name as the Necrosword andthe Godslayer after Knull's pantheon-spanning massacre left countless dead gods in his wake.
The symbiote sword soon passed on to Gorr, who became known as the God Butcher after the sword corrupted it towards its god-slaying goals. The end goal of Gorr's cosmos-spanning scheme was to use the sword to house a Godbomb that would destroy all deities past, present, and future throughout reality. However, the intervention of Thor saw the plan's defeat, since the God of Thudner was able to redirect the Godbomb's destructive energies against Gorr, and cast the weapon into a black hole so it could not be used again.
An object of such influence cannot be ignored for long, however, and it was quickly picked up in one of Marvel's futures. Galactus encountered the weapon when Thor tried to use it against him, before he was transformed from the Devourer of Worlds into the Butcher of Worlds. However, he saw the weapon then used against him in turn by Ego the Living Planet. Ego did not hold onto the Necrosword for long, however, and soon Loki claimed the blade as his own and declared himself the All-Butcher, and the villain has become more of a threat to his Asgardian brother than ever before.
The star-spanning weapon has not been confined to Thor comics, either. Its creator Knull has been a central figure in Absolute Carnage, as that crossover's titular villain plots to release the creator of the Necrosword from his prison on the symbiote homeworld. It turns out that the All-Black is actually the original symbiote, and that the homeworld of the symbiotes seen in previous events like "Planet of the Symbiotes" from the '90's is imprisoning Knull himself.
To broaden the potential role of All-Black even more, it may have made a fleeting appearance in Marvel's ongoing X-Men relaunch in Powers of X #4. In a flashback sequence, a group of demonic invaders used an all-black sword to slice the mutant island of Krakoa in two before Apocalypse turned them back to where they came from. While there's no guarantee that this was All-Black the Necrosword, it's inclusion could give this powerful weapon an even more ominous role in Marvel history.
Even if it wasn't in Powers of X, All-Black is still a key part of some of the biggest ongoing storylines in the Marvel Universe. With a history of prominent wielders like Loki, Gorr, Knull and Galactus, All-Black the Necrosword is quickly becoming one of Marvel's most sought-after items. Considering how strong and how evil it makes anyone who uses it, it wouldn't take much of a push to make it as prominent as the Infinity Gems have been over the past few years. While the multi-color Infinity Stones defined what power was in the Marvel Universe for years, All-Black the Necrosword could indicate how dark power is about to get within the Marvel Universe.