-spd +def Legendary Ephraim build

Wanna make him double and destroy weak mages, then hold his own against remaining physical enemies?

Death Blow
Solar Brace
Whatever C skill
Assist - reposition or smite or swap
special: Sol or Glimmer
seal: heavy blade

L'Ephraim dishes out a ton of damage with his default weapon's ability to double when he's alone. If there are any weak mages on the enemy team, L'Ephraim will easily destroy them on Player Phase. The Solar brace and special keeps him healing. Hell, you could put Aether or Galeforce on him too, for knocking out more foes or surviving longer. Those are excellent L'Ephraim ivs.