I agree with the idea of a personal limit break in addition to the party LB. call it something else if you want. But IMO this would be an area where you could customize an ability. Let tanks pick dps or healing skill, choose between single target or AoE etc . And make it all different questlines to unlock the different choices. obviously dont make it OP it should be something that gives ure job some flexibility or added utility.
This gauge would fill in much slower since its only based on ure actions and not party wide actions.