Hehe this is a silly idea but it would be kind of neat to have another class of jobs (Disciple of _______) that leveled up for certain parts of the game/minigames.

for example:

Duelist (cards) (Duelist AF gear hehehe) Levels could be used to gate certain cards if there's some sort of balancing system they want to put in, maybe abilities to invoke certain rules or conditions.
Tamer (pets) Levels would gate certain pets, abilties to tame them come with levelling
Mediator (parley lol) Abilities to better negotiate as you level, or take on harder foes.
Machinist (repair and maintain your machina for a PvE/PvP battlegrounds that use them)