Wondrous Item, rare
This blade was made by the aasimar. It is rare and extremely powerful.
Blade types: Longsword, Shortsword, Rapier, and Dagger.
This blade glows a faint white when celestials are nearby.
This blade glows a faint orange when dragons or dragonborns are nearby.
This blade glows a faint red when demons or devils are nearby.
This blade glows a faint green when fey are nearby.
This blade glows a faint brown when undead are nearby.
This blade glows a faint blue when monstrous humanoids (not including shapechangers) are nearby.
+3 to attack bonus. Triple the original damage die of acid damage against any of the types of enemies above.
What happens if more than one creature of the listed types are nearby? Or if their not only nearby but the same distance from the blade? Or if a creature is more than one type, like an undead fey? Or if there's an overlap, like a dragonborn possessed by a ghost?
Honestly didn't think of that. So just whatever you or your DM wants I guess. Your game right. I just thought it would be a cool tool. Maybe different parts of the blade glow. It's how you want to incorporate it.