Bride Tharja B Skill

Desperation seems like the most obvious choice.

She has great atk and spd, especially with her weapon and A skill. Her defensive stats, on the other hand, suck. It's probably best to build her as a player phase unit.

Vantage could work as long as she is able to one-shot her enemies, I suppose, but her spd stat kinda goes to waste... Also, she is gonna take some serious punishment from any enemy she is unable to one-shot.

Why use Aether, tough? It takes really long to activate, and it has poor synergy with both Desperation and Vantage...

I use Swordbraker on my +Atk -Spd B-Tharja, but with Neutral Spd Desperation along with Reciprocal aid/Arden Sacrifice(for avoid some battles ) can work fine.

My pick would be desperation. I use it and as long as she's next to 1 ally she one rounds most anything with less than 38 spd that isn't a high res blue.

Give her 1 more adjacent ally and she'll take out an unbuffed Nowi too, who would otherwise kill her on the counter.