A wacky Legion build

Hmmmm... I like it, yeah. You might see what you think about swapping Sack o' Gifts for Slaying Axe, maybe try running some sims using something like Kagerochart or somesuch.

Since you don't really want to run QR, instead opting for more defense. If you go Slaying Axe, it will make Moonbow on a 1 turn cooldown, allowing you to proc it on your retaliatory hit, and get the +10 damage from Wrath. It won't be a problem as much if you can double a character, but at 40 speed (38 if you go Slaying Axe), without some other method of buffing it, will fall against the speedier units nowadays. If you can't double them, or if they double you, you will have to wait until they engage a second time before you can proc your special. If, say, Legion's up against a unit like Raven, probably means that the enemy will be in Desperation range and will proceed to nuke your unit. Just a thought. Looks pretty good!

hmmmmmmmmm, wrath feels out of place with his immense health pool, maybe guard would work a bit more efficiently? possibly use QR just to make sure he always procs moonbow when QR is in effect?

on another note

those stat gains satisfy the hell out of me

I wouldn't recommend that, but if you're going to do it, slaying axe is probably better. Instant wrath moonbow retaliation.

With defenses that thin you don't want to let them attack into you, you want to initiate. Plus, with 38 speed I wouldn't necessarily expect to double back; in fact, I'd be content not to get doubled. After one round of combat you're probably not going to have enough HP left to bait again, so fierce stance isn't going to be doing you any favours.

Are you a big fan of enemy phase play? I wouldn't choose Legion as your go-to except to pick off some blues so that your red tank can sit and bait all day.

EDIT: some others suggested that he has too much HP for wrath. I don't agree; his defenses are low enough that he'll drop below 75%, which would make slaying axe all the more sensible. If you're going to go all in on OHKOs, fierce stance makes some sense. They hit you, +16 dmg moonbow BAM. Your turn, +10 dmg moonbow on your choice of target, BOOM. But then refine the slaying axe for mt and not for def.

I'm not denying it wouldn't work; it definitely would. His best go just tends to be as an offensive unit, and by a big margin. It just looks like an expensive build (two seasonal units, a Zelgius & Nephenee).

If what you're going for is variety, then you can keep doing it. If you're looking for suggestions, then I'd go for something more offense-oriented.

Also, if you have an S.Alfonse to fodder off, I may as well just give him the spoon.