I think you are really underestimating damage boost from attack buff. It should be around 15-20% more damage, that's definitely not negligible. And what the fuck with "one ability", which one are you counting ? Or better question: which one you don't ? Damage cut or damage buff ? I don't care what you think about "50% damage cut with terrible up-time", but this shitty skill can give you two or three turns (or even more), which may or may not be game changer.
Also, for goddamns sake, you have Kamihime with two party wide buffs (both quite strong) and said Kamihime also can keep up with rest of team when it comes to FB, how can you not call this "team player" ? She may be good, she may be bad, but that completely doesn't matter when it comes to calling someone "team player".