dunno if there is a damage type arc blade hunters are weak to, but its certainly not void damage (i have never killed a non-weakened arc blade hunter using a shotgun, even at point blank range). granted, i have killed arc blade hunters who were to far away from me many a time. are they weaker to arc damage? they seem to die easily to sniper rifles (my sniper is arc, shotgun is void/fire, heavy is fire)