1.Rather than making marche a ninja I have a stronger build for you
Fist make him a archer then a hunter, master the ultima shot, sidewinder, and especialy sonic boom, after wards make make him a soldier and learn combat combo, a fighter for strikeback, then finally a paladin learn all skills you can learn for paladin. Then equip him with 1. Mastersword 2. Diamond helm< or any high def. Helm> 3. Adaman armor 4. Mastersword< for the meantime if your sequence is not that strong yet> 5. Dashboots, and angel ring.
What makes him strong is the hunter skills esp. Sonic boom is AOE without using MP for the skill your damage will e 200+ all the time. And Ultima shot it could go 600-900
2. A perfect support for marche
Get a white mage then learn all it's skills then make it 2 a sage.. Giga flare will hurt any enemy