I'd make his power match his personality. So I'd make him brawny. Like super-strength. I know this is stereotypical, but that's what I'd do. Or, I'd make him have a wimpy power. You could make him have a power that when he plays music/sings, he can influence people.
For example, make them fall asleep, blow their eardrums out, make them happy, make them angry, etc.,