Class help

[Niwashi]

Plus once you get one class to 50 you get an EXP boost of I think it's 50 % to all other classes you want to level.

That doesn't require a level 50 class. It applies whenever your current (combat) class isn't your highest one. For instance, someone whose only classes are CNJ 17 / ACN 12 would have the 50% bonus as ACN.