I don't see much reason to differentiate the 2. They already play completely different, and it looks to be more so in the coming patch. One is reliant on their different combo's to be effective, one is reliant on their cool downs.

The only thing I would do to differentiate them further would be improve the PLD's oaths to make casting cure effective. Spell speed + on Shield Oath so they can cast spells while tanking and toss out a few cures to help ease the healers a bit. And a cure %+ for Sword Oath, so when they OT they contribute survivabilty to the party and effectively act as more of a supporty OT role, while WAR acts as a DPS OT role.