Further to my last post - I'm pretty sure that the only skills I could upgrade further in FoV were lockpicking and regeneration (at least out of the ones I used).
Are you sure you can't train it to level 15 after the second skill upgrade? You need to buy level 13 first, then level 15 should be available.
Also, I chose the female trainer - maybe the male one isn't as skilled? I've wandered if there were differences in the max skill levels between the trainers, but have only played the game through once.
