Please do not lock Jobs to the Weapon Class that unlocks them.

[Amineri]

... The only way I could see it going your way is if they made major changes to the armory system, because weapons are how we switch class, and jobs arent classes.

...

The easy solution is to have your class defined by what weapon you have equipped, and your job defined by the armor that you wear.

Wearing "generic" armor ~~> no job equipped
Wearing "Job" armor ~~> job equipped
(note: can only equip Job armor after unlocking the job)
This would all fall nicely under the armoury system, both class and job.