Wondrous item, common
This tiny chunk of glass or the gemstone is a result of the hedge wizard or the novice spellcaster attempting for weaponize the magical prosthetic eye. Even though it has been lost all its primary function and of course it could no longer be safely used for replace the missing eye, it is still easier to use and also it can make the serviceable secondary weapon.
You may be used an action for attach or else remove an eye from your forehead. So then once per a minute during worn, you may be used a bonus action for causing it to emit an unfocused burning beam towards the target almost within 60 feet which you could see.
Basically, this attack can deals 1d8-4 fire damage, it is dealing no damage if the result is 0 or below. So then on a natural 1, you are instead to take 1d6 fire damage as an eye misfires.