Barefist on a mage combo is really effective, ive made really good use of that in the past.

Blue magic on a monk or samurai is another good one. Most of the blue magic spells are'nt determined by how high your magic power stat is. Its the HP based spells that will be more effective. Whitewind heals your party for the current amount of HP the caster has. And ???? deals damaged equal to the amount you've received. So high HP classes like samurai and Monk will be most effective with these spells