BleuVII, thanks. Do you know if it would be possible to add all dark/holy knight skills to the onion knight? Or it is hardcode the no skills of him?
Hmmm... this may be a better question to bring to the War of the Lions forum, but as my answer will give you info about this patch in particular, I'll post it here.
There are 2 classes that you can do absolutely nothing with, aside from changing their job requirements: The Mime and the Onion Knight. The Mime is the easiest to understand. Mimes can gain JP and learn new abilities. However, they cannot equip any reaction, support, or movement abilities, any abilities that they learn cannot be used as a sub job, and any reaction/support/movement skills they learn cannot be equipped, even by other classes.
Onion Knights are almost exactly like Mimes, but they also cannot gain JP. Therefore, you can give an Onion Knight a skillset, but it HAS to be filled with skills that cost 0 JP; otherwise they cannot use the skills. Additionally, they can learn skills by being hit with them, but if they learn one, they will in turn learn their whole skillset at once. So... all of that said, the Mime and the Onion Knight kind of have to stay the way they are.
I had tried to use the intricacies of the hard-coding to the advantage of both of these classes. Blue Mages don't work in FFT because monsters use an entirely different stat progression system than characters to make up for their inability to equip weapons. Since the monster skills draw from those stats, a Blue Mage would have to match the monster stats, meaning that any sub-class would be incredibly overpowered on a Blue Mage, and the Blue Mage skillset would be incredibly UNDERPOWERED when equipped as a sub-class. So I tried to give it to the Onion Knight until I ran into the glitch with them learning all skills at once. I can try again on Mimes, but I think there was a reason I scrapped that idea.
EDIT: Also, it should be noted that there are more classes that you really can't edit: Chemists, Archers, Ninjas, Samurai, and Arithmeticians. The only way I managed to edit the Archers was to do a 3-way sprite swap between the Soldiers, Archers, and Monks.