Bards Limit Break should be some sort of group buff. Bards are damage dealing supports and their limit break should reflect that.

Rank 1 Increase Group Damage by 10% / for 10 sec
Rank 2 Increase Group Damage by 20% / Increase Group Healing Actions by 10% for 20sec
Rank 3 Increase Group Damage by 30% / Increase Group Healing Actions by 15% / Group HP/MP Regen for 20sec