Break the Trinity System Please

[Skullmaker]

There really isn't a good way to add such a class/job as it would mean re-programming all the boss encounters in the game to counter/resist all of the new abilities such a class would add. The only real way to do this would be to add a new class/job which would be:
class/ Jack of all Trades: Which would use ONLY cross-class abilities leading to,
Job: Clone: Which would repeat the last used ability of the highlighted party member.