Real simple, someone wants to use Ninjitsu from Pac Rim but none exists on the skill list, he added one under the Ref Skill list, but when you try to create a weapon attack, say punch, strike, kick, etc it does not show up as an option in the combat section, only the existing martial arts show up. Seems like a pretty big oversight or people are just using some other martial art listed, but I wonder if there was a workaround as trying to rename an existing skill to Ninjitsu changed nothing.