I just realized that Sigismund in Warhammer 40k is a good inspiration for sword immortals. He goes from a boisterous and dutiful warrior to what is essentially an object of war. Purging himself of all passions and making himself into nothing more than a tool of the Emperor's will. And it's horrifying, as seen from the perspective of one of his opponents:
He never said a word. Never. Throughout it all, the Black Sword didn't say a thing.
The monster. The ghost. The mere shell.
What could be worse than this? What death could be as profound as this? What disappointment, what despair, could ever be greater?
Khârn raged at it. He howled in fury, coming at him again and again, shrugging off the wounds. He wanted the old one back. The one with some fire in his veins. He wanted some spirit. Just a flicker of something – anything – other than this flint-edged, iron-deep hardness.
They had laughed together, the two of them. They had fought in the roaring pits, and had sliced slabs out of one another, and at the end they had always slumped down in the straw and the blood and laughed. Even the Nails had not taken that away, for in combat the Nails had still always shown the truth of things.
'Be… angry!' he bellowed, thundering in close. 'Be… alive!'
Because you could only kill the things that lived. You couldn't kill a ghost, only swipe your axe straight through it. There was nothing here, just frustration, just the madness of going up against a wall, again and again.
[...]
'I… am… not…' he panted, his vision going now, his hands losing their grip, 'as… damaged…'The Black Sword came at him, again, again. It was impossible, this way of fighting – too perfect, too uncompromising, without a thread of pity, without a kernel of remorse. He never even saw the killing strike, the sword-edge hurled at him with all the weight of emptiness, the speed of eternity, so magnificent in its nihilism that even the Great God within him could only watch it come.
Thus was Khârn cut down. He was despatched in silence, cast to the earth with a frigid disdain, hacked and stamped down into the ashes of a civilisation, his throat crushed, his skull broken and chest caved in. He was fighting even as his limbs were cut into bloody stumps, even as the reactor in his warp-thrumming armour died out, raging and thrashing to the very end, but by then that was not enough. The last thing he saw, on that world at least, was the great dark profile of his slayer, the black templar, turning his immaculate blade tip down and making ready to end the last bout the two of them would ever fight.
'Not… as… damaged,' gasped Khârn, in an agony greater than anything the Nails could ever have given him, but with more awareness of the ludic cruelty of the universe than he had ever possessed before, 'as… you.'
And then the sword fell, and the god left him, dead amid the ruins of his ancient home.
- Warhawk, by Chris Wraight.
