Because the body mod needs to be purely aesthetic, i.e., it can't provide any advantages in combat, are you all right with the metal claws not having the ability to heat up? In addition, they'd be just as fragile as regular claws.

If you'd like to add some combat advantages to these claws, this would count as a minor power! Keep in mind that minor powers often have limits, e.g., they can only be used once per day. Let us know what you think.