Discount Duo Hero? That might be giving way too much credit to be honest.
Raven’s gonna die if he’s not desperate. Galeforce on Ephraim would be more interesting too.
The only problems with WoM Ephraim is that Flame Siegmund works when there’s more foes than allies and WOM may hinder his forced follow-ups. It’s best to keep Lull or use Desperation on him.
As for WoM Raven, if you can reduce his cooldown to 2 or 1 with Infanty Pulse/Time’s Pulse, you can have finish off enemies weakened by Ephriam without taking too much damage otherwise he needs desperation or repel/close call to reliably survive and defeat his foes.
A true warrior uses Ephraim with Lyon.