Running a Tactic skill on Setsuna seems a bit wasteful. If she has to stay within 2 tiles of an ally to get Hama Ya's Drive effect off, the Tactic slot is sort of 'wasted' there since the benefit of the Tactic skill is that you don't need to be around your ally for the entire turn. Running Drive skills sounds better for her. You end up needing to be near them anyway to get the Tactic buff up on the next turn too, but... hmm, well Setsuna herself has low attack and would like to get in on some atk buffs so I probably wouldn't put it on her anyway.
But yeah, I've been disregarding Tactic skills since it's kind of awkward when combining it with Light Breath, which I usually use. I can try it out though on Palla and see how it works out. It means I can swap out Odd Atk Wave on FCorrin for something else, though I don't know what. I tried Res Smoke but it doesn't seem to be as effective as I'd like.
edit: Atk Tactics is working pretty fantastically actually, gives FCorrin some much needed initiation power and Setsuna lots more power. Just have to make sure that my bonus unit is anything but an infantry. I was meaning to fill Palla's C slot with Infantry Rush if I managed to get it (after I'd been chucking all my orbs at it) but now I have no space for it anywhere. I guess I can stop pulling on that banner and, I don't know, save up or something. Every skill slot in my core trio is filled so I don't think I have to pull for any rare skill fodder for a while. We'll see.