Well, the girl is still on training and there is not enough time to rebuild her self-esteem.
So, the coach will have to fight fire (girl's ptsd) with fire (repeating training and drills).
That usually is the last resort for those serious cases if all other solutions prove to be futile.
Slams bamboo sword next to girl
Girl breaks down, cowering and keeps on apologizing like there's no tomorrow
"Must be her self-confidence, let's boost that"