I dont think it needs "you" to make an attack ...
It sound more like regular thorn aura, but only under 50%
Oh, true, I slightly misread the item. My mistake. I suppose "when is damaged by an attack" is a good enough proxy for "enemy gets very close to your armor"
Still, it doesn't really make sense that it happens only when <50% health. Is it feeding off of my blood and/or using that blood to deal this damage? That's a kind of cool idea, but not at all supported by the description. And imo a better item would be "you take 1 point of damage each turn, but in exchange if an enemy hits you they get dealt 1d4 piercing damage."
