There is literally no downside to equipping a shield, unlike some other games. There is no damage increase for having just a sword equipped, and you lose the stats you would have gained from your shield, so the argued loss of DPS is counterproductive. So there is literally no argument for this person not using their shield, stun is another thing but the general accepted strategy is to stun eruptions when possible so that you build LB and save the party hassle. But hey, if you guys are okay with people gimping your fight for lawls you won't mind when I come try to main tank in my snowman suit right?