Unfortunate hero with a cursed weapon they've grown attached to.

(A prompt-response to Making Up Adventurers)

The blade looks interminably old; it certainly predates what present-day blacksmithing considers best practices. It's positively covered in nicks, as if it has never been tempered or sharpened in its life, and by this point in its not-short lifetime, it even has some spots of rust developing around the hilt. The man at the pawn shop, years ago, had not wanted to assign it a price. Priceless? No, don't be such a fool, to sell this abomination onward would be to give it exactly what it wants. Another damned victim.

The town exorcist had a similar, albeit more detailed opinion of it. This crude, tattered blade from time immemorial bears two curses. You see, he had said, it has spent its lifetime buried, or submerged perhaps, and by now it may even have been centuries since it last drew blood. In such a state as this, its thirst may be so great that it may even refuse to be properly sheathed until it has tasted it once more. Even your own. But also, pay heed to this sinister red glow - there are some artifacts that we know, that will glow in the presence of its most hated thing.

Perhaps on the way back to the inn, this sword would be drawn in anger, against the sorts of ne'er-do-wells that would attack a hero in the middle of town. But a better-thinking hero might abstain from actually using it, especially if said ne'er-do-wells flee in terror. Best not to chase them. They knew not what they did, but now they know. They do not need further teachings. But oh, now, what to do with the blade, if it cannot be put away?

That night, the inn room is simply too dark. A hero that serves the light cannot be expected to be comfortable in such pedestrian darkness. But they remember the blade, still naked from the earlier incident, carefully kept under some folds of cloth to prevent it from slicing anybody by accident. The cloth is placed on the chair on the other end of the room, and unfolded. The cursed sword appears to be glowing with newfound anger.

There is no moon tonight to shine through the window. The old sword, its thirst resolutely unsatisfied, discovers a whole new kind of hatred. Its hellish orange glow, meant to signify its pure, condensed hate to its bearer, reduced to a mere night-light? The gall, the damnable insolence. In the night, the sword lay still as its new bearer sleeps. It glows jealously at the hero. Why should you be allowed to sleep so peacefully while another has thirsted for so many hundreds of years? It keeps glowing, with the energies of so many years of neglect. It hates this new bearer most of all. And this glow only makes them sleep more restfully, when all else is dark.