Come to think of it Red Mage could make a very interesting high risk/high reward tank. Sword/raiper for base combat, melee based fire/ice/thunder spells for damage moves, and a setup of highly situational buffs/debuffs/self heals for mitigation. A regain for sustained damage, a short lived mass armor buff for power attacks, a debuff for toning down AOE spam, that kind of stuff.
Make it the hard to play but unstoppable when played right tank class.