Free Minerva

She comes with LnD and some other skill, also due to new refine she basically has built in wrath which is great for Moonbow or Glimmer builds. I know the Atk Bane is horrible but you can fix that with LnD or Fury.

At least its not speed

Her best option is to go enemy phase. Try Atk/Def Bond with Quick Riposte and Moonbow or Ignis. With her refined Hauteclere she can proc Moonbow with +10 damage on both her counterattacks if she'd doubled, if she's not doubled she has a Moonbow or Ignis for player phase. That's the set I use on my +Def -Res, remember your atatck bane is only 3 points so there's not really that much difference.

If you have an aggro flier emblem play style, she should use Death Blow and Desperation. Atk banes don't suffer as much in flier emblem. Even outside of flier emblem, I would still recommend Death Blow over her native Life and Death because she has great def and ok res. She doesn't need Fury to get into Desperation range because she will take enough damage after one round of combat, saving you a turn and allowing you to sustain fights.

First of all, when people say "salvage" I think fodder. Salvage = try to pull something from what is no longer useful.

So I already think you're wrong. And I don't often say this to people - I might say they missed something or miscalculated or something, but this time I really think you're wrong. It is foolish to count a unit worthless because of an IV that conventional, run-of-the-mill, cookie-cutter recommendations dismiss out of hand. Counterintuitive to most, I think this is one of the best IVs.
- She can take multiple hits to her def especially if her A-skill boosts def, which means she's probably unleashing a bonfire every time (or even ignis if you can activate heavy blade somehow, but then you probably don't need such a massive special) for 25 extra damage, which alone probably compensates for the lost atk. As such, def is arguably her best boon, possibly even better than spd in light of my next two points. For banes, res is probably ideal for most purposes and HP next-best; given her weapon and the way flier buffs usually work (at least in my barracks) I would probably take an atk bane over a def bane, so third-best (and also third-worst) bane.
- Flier buffs usually cover any atk or even spd bane unless you start with around 30 spd after the bane, then it's harder.
- Most of the time, fliers prefer to stack goads, which means there might not be a ward around and she might not have received any fortify on the team (and if there is a ward, there's a good chance she's giving it away because she comes with it and it's slightly less common of a skill, though that has improved significantly with Shigure's demotion). Since the goads will push her atk back up anyways, def is the skill she prefers to increase through IV.