What is bonus exp?
bexp is the exp given to you for doing certain stuff right on a chapter. It can be used on any unit to raise their exp or level rank. However, it is not a one to one ratio, you will need more then 100 bexp to raise a complete level. Unlike in PoR bexp has a limit. Every time you use it, you will get three stat ups. No more abusing early game, but you can max stats late game for sure. If you do not use up all the bexp in a certain part, it will carry over, but only once that party is again in your main force.