I specifically only looked at the non costume versions. The stat boost and passive utility make a lot of them useful. C.Zeline is a good example.
Grace does defense down against special skills. C2.Caedmon dispels and blocks buffs.
So if I were to use Grace in my roster, I’d go Almur for EDD, Frigg for Defense Down, and then Grace to finish off. To take advantage of her special skill boost, I’d need a fourth hitter (in my case C2.Lianna or C2.Caedmon).
If you don’t have Frigg, you can move her up in the order.
I’d even rather have Evelyn than Grace as I could do Almur to one side, Evelyn to the other, then Frigg, and then my fourth hitter.
If things go well, I’m probably doing killing without Grace’s help. If things go wrong, I’d rather have buff blocking or silence (or even the small heal Evelyn provides).
And yeah, if I had El Naddaha, she would be preferable to most of these.
If Grace did even -24% regular defense down, I’d shoot her up to the top quartile. Or if her blocking wasn’t just taunt, if it was all buffs, then again I’d shoot her up.
Of course I could be very wrong.