Are you starting with a flawed assumption that a non maneuver non cast non skillpoint HD12 full BAB class that revolves around hitting people with 2 lightning weapons is not a one-track build?
Well Thunderstrike probably fits skirmish best, as it's a spammed effect.
Bardic music without resorting to specific powergaming builds does not actually grant anything close to what you suggested, and giving it that will not raise it's tier capacity. Tier is designed to measure the number of tasks it doesn't fail at and Marshal does not fail at it's role, it just has a limited number of them.
I'm not saying marshal isn't lacking, it does need a few more tricks to raise its utility to T3.
I'm saying that adding several times the power to an existing ability does not balance a class, if it did then balancing the monk out of T5 would be as simple as giving it a +5 to attack and tripling it's damage.