in TRPG2 the main was allowed to train his/her skills, in TSoG these skills increase with use. I think there should be a combination of the two styles.
For instance, having the trainer train you to the next level of the attack with the cost dependent on the amount of experience left to level (divided by 3 to represent individual uses of the attack, or just based upon individual experience points). Even having the possibility of choosing how many experience points to increase (say Duvalier only has enough gold for 54 points but needs 57 to level, he can buy the 54 and attack an enemy for the remainder 3) (this should probably be represented by a(an?) hpscrollbar to easily eliminate a majority of bugs that could arise, with the max value set to the maximum amount the main can A. afford or B. needs, whichever is the least.)
Discuss at your leisure. ^^