So in FF Tactics you could spend your JP to purchase 'Equip' skills, allowing you to equip weapons or armor not typically useable by your job class. What about a merit that allows you to equip one weapon from your sub job class? Say 10 merit points and you can pick one weapon currently from your sub, but not useable by your main. Then maybe make it where your current skill in that weapon is locked in, so you can't build on it. That would encourage people to level up other jobs and work on increasing their skill levels. Of course, the obvious disadvantage of this is the fact that not every weapon is suited to a certain jobs. My RDM might look cool running around with a scythe, but beyond that, I wouldn't benefit much. Just throwing it out there.