Fjorm

The neutral is the best IMO. cause fjorm is one of the few units that benefts in every stat and you don't want to decrease any of her stat.

Me personally I would go +atk -def because I've been using a -def +res Fjorm and she's worked wonderfully as a mage baiter with Warding Breath and Distant Def, but that's just my play style when I use her. Fjorm is one of those few awkward units that uses every one of their stats, so either you wanna risk it with a trade off or play it safe and stick with neutral. It also doesn't help that Fjorm has three superbanes for SOME reason.

Honestly I’d go with neutral. The only “safe banes” Fjorm has are res and HP. A def bane makes her too squishy, an atk bane makes her hit like a wet noodle, and a spd bane makes her go from respectable to being doubled by a Hector with a Hone armor buff. Her attack is her best boon, and lowering her HP sleeps her bulk and other skills intact, and her RES dropping makes Ice mirror against mages hit harder. I have a +1 merged +atk-res Fjorm and she is a beast in arena. But the residual loss in res makes it harder to use her in PVE quests, which I learned the hard way in GHB when I needed to boost her res enough to let her not die.

These answers are all wrong, don't listen.

+Spd -Res is a great IV, because you can run L&D and actually make Fjorm fast.

Plus, Fjorm WANTS to lose Res, so that she takes more dmg from mages and deals more with Ice mirror.