I wouldn't mind seeing something like Chivalry from XI, which converted TP to MP at a certain ratio. That might assist MP problems PLD's could potentially have.

However their MP isn't necessarily the problem. WAR does a ton of damage, has higher HP, and is a beast in Rampage mode. With the accessibility of crit rate+ gear and the HP you can gain from Mogaxe, WAR is a self-sustaining powerhouse right now. PLD isn't going to ever do that amount of damage so they've gotta give it something so good that people will want them over WARs for another reason.