WARNING: This article contains SPOILERS for Weapon X #16

At long last, Wolverine has finally killed Sabretooth - for good. The pair of regenerating, wild mutants have thrown down multiple times throughout the history of Marvel Comics, yet there has never been a clear winner, or a true death of one at the hands of the other... until now!

In Marvel's Weapon X comic series, Old Man Logan and Sabretooth are on the same side (for once), along with Domino, Warpath and Lady Deathstrike as part of a new team of Weapon X test subjects, banded together as a mutant rescue team. But that doesn't mean they have to like it - or that old habits die hard.

In this week's issue of Weapon X #16, titled "Blood, Sweat and Claws," it's Logan's birthday, and fans of the character know what that means for Sabretooth. The one-time nemesis of Wolverine, Sabretooth has made it a tradition to hunt Wolverine down and attack him on his birthday, and although the current Logan is technically from a different universe (that of the post-apocalyptic future seen in Old Man Logan), that kind of detail isn't going to stop Sabretooth from having his birthday fun. Although it means a death scene for the ancient mutant this time around.

The issue starts with the two attacking each other on an airship, which has crashed and sent Logan into a berserker rage. He and Sabretooth are tearing each other apart with the help of a handful of horrific beasts in the containment facility where they landed. As a way of putting Sabretooth back on his figurative heels, Logan reveals for the very first time exactly what happened to Sabretooth in his original timeline.

This Sabretooth still stands, but the one that lived to the future Wasteland? He's dead and buried, by Logan's own hands.

Blood Sweat and Claws, Wolverine beheads Sabretooth

In the wasteland, Logan reveals, Sabretooth had given in entirely to his animal instincts and losing any control or semblance of humanity. That seems to be what finally allowed Logan to take him down for good: beheading him easily, and then cutting his body into tiny pieces, boxing them all up, and burying them so that he was unable to regenerate. Ouch.

The reason for Logan letting Sabretooth in on this particular story isn't just for the sheer joy of learning more about the hugely popular Old Man Logan world (although fans will appreciate it). It's because Logan is struggling with Sabretooth's 'moral inversion,' as the one-time villain feels his old self beginning to return - as evidenced by the traditional birthday attack. But just as Logan is going to try and kill Sabretooth a second time, in this universe... the clock strikes twelve, and Sabretooth abandons the challenge completely.

The partnership between Logan and Sabretooth may be more or less reliable and stable, now that both are aware of exactly where this rivalry will lead (and already has once before). Expect this 'moral inversion' plot to get even more complicated, for Logan as well: now forced to at least try to accept this Sabretooth as human, when the one he knew was a true monster.

Next: Wolverine Is Dying Again (But Not The One You Think)

Weapon X #16 is available now from Marvel Comics.