That girl is way too easily impressed.
She seems to be fangirling over karate... but the fact of the matter is that 99% of that guy's effectiveness is in his personal strength and his protection by the curvy goddess. Even if she had exactly the same skill he does, she wouldn't be anywhere near as effective because she is a small, unprotected weakling.
There are martial arts far better suited to be learnt by waifs that are more dependent on skill and less on just being a muscle-brute.