Full Set: 2
When the player wears this helmet and carries the ancient sword while passing anubites, they will mistake you for Anu and will not attack (unless provoked). Also, in 7.3, when the helmet is worn while striking a pig with the sword, the pig will become a tamed zombie pigman who will protect you when you are attacked and kill mobs that you attack. Note that striking a pig without the helmet only creates a regular zombie pigman.
To restore the durability, place it into an archeology workbench and it will be repaired, but any enchantments you put on it will be lost.