k I think there’s an argument to be made for giving her flashing blade 4, especially if you want to free up the seal for a teammate. Then I guess you take a brazen seal and that’s a ton of atk. It seems potentially overkill to me; I might even prefer to use the seal to support teammates at that point. Considering the point on overkill, maybe death blow 4 (or 3) + flashing blade 3 is enough so you just go with that and someone else can get the flashing blade 4 and/or NFU.
I think there’s also an argument for null follow-up, but it’s quite specific. It’s for AR defense (because WoM will activate and all manner of chaos will break loose) or if you’re like me and looking for “can-openers” for galeforce teams, null follow-up looks quite convincing on her.
One-round aether is possible with spiral, but I don’t think it’s good on her unless aether activates on the first hit, which isn’t reliable. A lot of opponents won’t have much HP left to give her after she hits them once. Better would be sol, but that’s probably better on the prf blade tome with the in-combat atk debuff on the opponent.
Generally speaking, I think it’s ideal to be able to fodder both flashing blade 4 and null follow-up, which currently requires sacrificing a Mia. If you don’t like that idea or it’s not even possible for you, one option is to wait and see if flashing blade won’t appear on a GHB/TT unit.