It was pretty well-known that the only subjects Melissa didn't ace in the military academy had to do with one-on-one combat. 

Melissa still has a faint scar on her midriff, but I've never canonically drawn her midriff (yet????) so no one but her has seen it. She's mostly indifferent to it. (She's embarrassed about the scar on her shoulder she got at the end of PF.)