There is one weapon in the Marvel Universe that is able to cut through every known substance, including Wolverine's adamantium skeleton: the Ebony Blade. This legendary sword is usually wielded by the Black Knight, and it already made its debut in the post-credits scene in Eternals, which shows Kit Harrington's Dane Whitman opening an ominous case that contains a black sword - the Ebony Blade.

There are very few things in the Marvel Universe that can damage adamantium, which plays a huge role in what makes Wolverine so hard to kill. The blade was forged by Merlin, who enchanted it with a curse that causes any that use the Ebony Blade to become overwhelmed with bloodlust, getting worse with each death it brings. Dane Whitman has been able to overcome that bloodlust, which makes him the hero and Avenger that he is, but others who wield the Ebony...