I love the ideas that have been come up with so far, but I would like to offer another suggestion. I'd like to piggyback off the last post as it's a fantastic idea.

I would suggest a Trance like mode as well. You fill up your Limit Break meter to full. You can then activate it whenever you like in battle.

When you activate it, you enter a Trance like mode where your character glows with power and gives you a buff based on your class.

Gladiator - Increased Defense
Marauder - Increased Damage dealt
Lancer - Increased attack speed
Archer - Increased critical hit rate
Conjurer - Increased magic potency
Thaumaturge - Decreased MP consumption
etc.

Also, while you're in this Trance mode, your TP flares with a red color. You gain special and Epic TP moves specific to your class that can be performed at 1000, 1500, 2500 and 3000TP. With the 3000TP Limit Break TP move being your "Ultimate Attack".

Gladiator - Ultimate End, a 13 hit sword attack.
Marauder - Shattering Stars, a spinning cyclone dealing 6 hits of damage, ignoring a targets defense.
Lancer - Wrath of the Dragon, a stunning leap into the heavens, crashing down upon your foe with extreme force.
Archer - Skyfall, Fire off a barrage of arrows into the sky that detonate and rain devestating shrapnel down upon your foes.
Conjurer - Meteor. 'nuff said.
Thaumaturge - Transfers all buffs from your enemy to a target member of your party.


Once Trance is activated, your Limit Break meter flows backwards with the total amount of time allowed in Trance being dependent on player Rank or some other catalyst.

During this time, you gain your class specific buff and specialty skills usable with your "Limit" TP.

This brings together alot of the ideas presented here. Limit Breaks requiring a long build up, awesome moves using Limit TP, a reason to use them with proper strategy.