What if we wrote up and shared NPCs in a way similar to the way 1st edition AD&D handled artifacts?
Instead of long backstories, you would be limited to a paragraph, two at most, describing the person. Then certain strengths or weaknesses would be left up to the DM. Maybe the "powers" would be something like Minor Weakness, Minor Strength, etc. Or, maybe Flaws, Vices, or Quirks?
Hmm, not sure, seems like what's interesting about characters is their specific strengths and weaknesses. "Frail, albino noble with a soul sucking sword" is pretty explicit isn't it? Maybe what "frail" means or how soul-sucking would work mechanically would be left to the DM?