Not only Brann is a piece of sh*t and also too full of himself, but, worst for me is something else ... who in the world vicking as no respect whatsover to blacksmith ?!? I know, you will all said no-one care about that in the story but, guy ! Don't spit on history and commen sens please ! Blacsmith are with warrior and nobility the three great job/classe in Nords mythologie ... so this is clearly bulsh*t. No warrior talk and act like that against a blacksmith !
I thought the weapon corrupted Brann which is why he acted like that during the war but he seems to be the same even before he got the weapon that brought his downfall according to Ana. So he never seems to have been that great of a guy but I guess the weapon made it worse though he would have caused his own downfall even without it.