Recommendations for BK's B skill?

Wrath just gives him that bonus extra damage for his Black Luna to help him destroy blues who happen to survive an attack from him. I personally use Vantage and it's fine.

Note: I wouldn't recommend Life and Death, it's better recommended on squishy units and Black Knight is hardly squishy, he can take hits so don't run this on him. Plus 1 movement is gonna screw him over and his Draug-level defense is much worse.

For all around purposes, vantage is better than wrath. Wrath is more specific but vantage is overall a more threatening option. You can mitigate wrath build, but vantage build is much tougher.

Sure there are specifics that makes wrath really good. I still prefer vantage on both pve, arena, and especially TT.

Vantage sounds like a good option, if you dont want/ or not have a extra B.Ike or Nephenee for use.

I am planing to run with Fury-3 and Vantage-3, since a dont have the "optimal" skills.

*Long read, just skip to last paragraph*

Wrath is the single best B-Skill on him. Assuming no merges or buffs on him, he can do 60 x WTA - Enemy Defence x 0.2 on every single retaliation with Steady Breath, which, if you do the maths, will one shot basically every unit in the game, regardless of colour, gender, or race, even without additonal attack buffs. BK don’t discriminate.
Now if we keep in mind how Wrath and Black Luna works, every single attack for BK is basically the difference between whether something dies or lives, similar to how speed works.
Although without Steady Breath, the potential of Wrath falls significantly since Black Luna won’t proc on every attack. However, due to Wrath’s passive CD reduction on every turn and his insane physical bulk, it can still be used to a similar effect with Steady Stance (not Fury).

I personally think QR is his second best option since, other than blue and red magic dealers, basically nothing can kill him on Defensive Tiles, and this mixed with the fact that his speed acts as a Wary Fighter. I can’t tell you how many times my BK has solo killed 2-3 enemies in Arena without even going below 70% HP.

Finally, coming to Vantage, I think this skill is actually a really offensive option for most units. It’s fantastic on units who have both a powerful player phase and enemy phase. Units like Ryoma, Buffed Fury!Camus, Minerva, etc, can all make great usage out of it due to their offensive power on both phases (speedy DC units) or Vantage’s ability to provide protection on enemy phase (Minerva, Nino, Tharja).
The one exceptions to this case is of course, non other than Hector, and for use Arena Defence. In Hector’s case, his access to Armads allows him to have QR and DC when at high HP, Vantage and his high attack stat to protect him when he falls out of QR range, creating the perfect combo.

So, all in all, I think Steady!Wrath and QR are his best baiting options since they help him kill more / do more damage, while Vantage is his best offensive option, especially with Armour March or Guidance, as it protects him from dying on enemy phase after fighting someone on the player phase.

Hope this isn’t too long a read, I just want to help you decide for yourself instead, since all we can do is provide one perspective on the matter from personal experiences.

Edit: Oh, to actually answer your question though, I think just stick with Vantage untill you get Steady Breath. Since QR2 doesn’t give as much Arena weighting as Vantage 3 and Wrath isn’t as good without Breath.

Player use: Wrath or Vantage.
Arena Defense: Wings of Mercy