Scars would be a cool addition, personally I think it would be interesting if they added scars as a unique reward for each Extreme Primal you fight. Either make it like the hairstyle(an item you need to gain) or just have it be an achievement but they could have fun with it. With the burn scars from Ifrit, Frostbite from Shiva, Lightning(Lichtenberg figure) etc etc. Would be some fun flare to add to characters. Maybe have the ability to unlock the ability to use more as you gain more scars.