Barbarians already use emotion as power. Their rage, which is an emotion, fuels their strength. What the player is asking, that the rage fuels his emotion, doesn’t actually make sense. The Barbarian didn’t get the extra strength from strength. He didn’t get pumped and that gave him damage resistance. He got MAD.
So no, to be honest his question is rather silly. Go with it if you feel it should be ok, but would force the advantage from Rage to be Charisma, too. Not sure where the resistance would come from, since he’s apparently just getting more attractive, or more forceful, when he rages, rather than getting stronger. Maybe his sheer force of personality makes the enemies not want to hit him? I don’t know. It doesn’t make sense to me.
I’ve had a Barbarian Wizard in mind for a while, wanting to see how that would work, but I’m not going to ask my DM to let me key the Rage off of Intelligence.
So no, to be honest his question is rather silly. Go with it if you feel it should be ok, but would force the advantage from Rage to be Charisma, too. Not sure where the resistance would come from, since he’s apparently just getting more attractive, or more forceful, when he rages, rather than getting stronger. Maybe his sheer force of personality makes the enemies not want to hit him? I don’t know. It doesn’t make sense to me.
I’ve had a Barbarian Wizard in mind for a while, wanting to see how that would work, but I’m not going to ask my DM to let me key the Rage off of Intelligence.