Is Brave Ephraim's Weapon Garm affected by dancers?

It says it requires buffs from either assist skills or "C" skills or can be active by a skill like armour march or armoured boots. So I'm going to assume not but I could be wrong as I haven't/can't test it.

I just tested this. Ephraim was fighting someone with equal speed to him, and after receiving the buffs from PA Azura's Uror, he double attacked. The buff is only +3, which doesn't put him in doubling range, so I suspect his axe simply looks for out of combat buffs, like the +1 to mov armor march gives him.

I'm going to say yes. It refers to Rally/Hone type skills as well as Armor March and Armored Boots seal, so I think Dancer bonuses from weapons & B slot skills and Forify/Hone C slot skills will also apply.