Felicia ivs?

Spd. It helps her offensively against fast units and it helps defensively against fast units

One of the -def ones seems better unless you plan to stack DD3 on her.

I strongly suggest +atk because she's the only one that can circumvent the high def of a lot of units provided they don't also have good res, in which case you're going to have to find a way to grind it out with Saizo, maybe using CC+close def+guard or something.

-def and -HP are pretty similar; both would probably require desperation if you're going with my above idea. She usually won't survive more than one hit to her def either way. The question might come down to whether she or Kaze is the one who will try to deal with pre-charged glimmer on Lilina.

+Spd/-Def

Dagger Emblem Forever!!!

Not an expert here, but I just recently 5-starred a Felicia, and I waited for a +Atk one (can't remember which bane I went with ATM). I have so many +Spd dagger units that having a +Atk one for her seemed good to me.