I actually didn't change classes until later in the second disk when I remembered you could. I at first gave Shu some Monk skills, Jiro Black Magic, and Kluke White. Now, that I have Generalist 18 for everyone, I have Shu an Assassin (Got every skill on Sword Master) Kluke and Jiro are leveling up in Black Magic (Jiro has everything I want in white) and I have two other characters (I'm going to let you find them out

) Who are now Sword Masters since they are done in either monk or assassin.
The only problem there is with doing this is that 2 of my front 3 have hardly any MP. But that isn't so bad when Shu or Kluke can easily send out 1000 damage.