Armor of Vulnerability
Armor,
Rare
(requires attunement; cost 4000 gp)
Crafting Components
Fool’s gold and rust left over from a rust monster’s attack
This armor grants you resistance to one of the following damage types: bludgeoning, piercing, or slashing. The type of damage is determined when the armor is created.
Cursed. Once attuned to this armor, you are cursed until you are targeted by remove curse or similar magic; removing the armor does not end it. While cursed, you have vulnerability to the other two damage types this armor does not protect against.
Source