About that aura idea.

Maybe instead of someone good or evil being able to have no visible aura, the aura of a true hero/villain could be enhanced. I'm not sure what color they'd be, maybe just an extra word to say they're particularly bright, or make it apparent to those who can't normally detect auras.

I think it would have to be entirely an RP bonus thing, but I'd personally rather have a permanently extra shiny/dark aura than an extra handful of xp. For the player it could be a badge of honor to be one of the rare few to receive it, and it would bring an obligation to keep RPing well or lose the aura boost. And it doesn't even have to do anything special.