Eye of Polyphemus

An artifact of the ancient world, the eye of Polyphemus is a fossilized orb over 3 feet across with a hole in one side and geode-like crystals lining the interior. It carries powerful magic which is both a curse and a boon. A person in possession of the eye is struck blind, but they are granted the physical durability of the legendary cyclops and the ability to sense deception from others.
The last person known to possess the eye was a minor lord of faerie named Ruaidhrí who about 300 years ago sequestered himself away from all his attendants and hasn't been seen by a living soul since.