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His what?
A Chinese two-string fiddle, apparently. I'd never heard of them either.
Depending on the character, it could be Cultured Warrior or Warrior Poet
Dunno, "plays an instrument" is kinda People Sit On Chairs. Depends on what that erhu says about him, it could be Cultured Warrior as suggested^, or something like Elegant Classical Musician.
Just to throw them out there, this could also be used to give a character Hidden Depths or as a Dreadful Musician gag
I found "Cultured Badass" and thought it fit him best.
I'm trying to create character pages and a certain character likes to play his erhu just for fun. Is there a trope about that?