Tanegar: I figure its the cost difference. It would be silly to pay 10, 20, 30, 40 karma for getting Martial Arts 4 post-chargen (100 karma for a 20 BP quality).
QUOTE (Dr. Funkenstein @ Apr 16 2010, 10:37 PM)

They're stepped. Martial Arts 1 is 5 BP total, 2 is 10 BP total, 3 is 15 BP total, 4 is 40 BP total. If going from 3 to 4, it's only 5 BP.
I was unaware that you could get BP after chargen.
(Or to be less sarcastic: he wasn't asking the BP cost, but the karma cost to improve post-chargen)