Jean's the Frog Prince of Sima Fort, and one of the most pure-hearted beings in existence. Jean joins you briefly when you lift Nimufu's curse on him, and joins you for good once you defeat the impostor that seeks to usurp him.
Fighting/Defense -- Jean is your slowest character, and his attack is about even with Sten. His defense is a little better. Jean as just plain Jean isn't worth much. His weapon is the rapier, and he has access to most armor.
Special -- Jab. Jean damages all monsters on screen. However, the more foes there are, the less damage he does. Any bonuses his weapon has for damage don't apply here. I only use this on groups of weak foes with poor defense.
Magic -- Jean learns an assortment of spells, of many purposes. Jean has only a little more AP then Sten, but his spells don't use much AP. His only damaging spell is Cold, but he'll also learn the instant destruction spells Angel and Death. He's a good candidate to learn Missile.
Shamans -- Holy or Holy + Water or Wind results in the Paladin. When Jean is in this form, he's finally worth a damn. Attack gets a big boost. His Special changes to the infamous Chop. When you use Chop, Jean does nothing for one round, and then one of two things occurs the next: 1) Nothing (only with bosses and a few certain monsters) or 2) Every foe on the battle field is destroyed (you'll see 999 damage, but monsters with more HP than that will still die). With the Paladin, you can win most battles in two rounds. Chop works on undead.
Field -- When traveling the world, Jean can turn into a giant frog. As the frog, you can travel through rivers and hop over small cliffs and lone trees. The frog covers two steps with each hop. The Paladin can assume frog form.
At level 40 -- Jean has all of his magic, which also includes such nifty things as Warp, Hush, Idle, and Renew. Jean's still weak in attack and speed, though his defense and HP are all right. If you want an ultimate holy warrior, then do the following -- get the NoTwin Rapier, use a lot of PARs (Dinkers and PwrFood, especially) on him, and turn him into the Paladin. Believe me, it's worth it.