That seemed... really unnecessary, to be honest. Like, I get that Goblins is a gorefest, and for the most part im, if not OK with it, then at least accepting that smacking somebody with a sword or an axe isn't going to be pretty. But having to resort to self-mutilation to use a random magic item is just... why? The fridge logic kicks in here a bit, there really isn't any good reason for the helmet to not fit Big Ears even though it fit all the other goblins' non-standard head shapes. Its magic, its literally supposed to Just Work, by design.