The Glowing Eyes is a Halloween Event exclusive cosmetic armor type originally designed as a feature to make the new RUST Murderers more identifiable to players. It was introduced during the 2017 Halloween event but does not make it into these events as an item available to find by players.
This cosmetic-only addition does not occupy any given slot exclusively, meaning that it can be worn with any eye-covering or helmet available so long as you have an armor slot available. It also offers no defensive statistics of any kind, making it solely cosmetic.
The only way that this item can be acquired is through administratively spawning them via F1 Console. The glowing eyes also hold the distinction of being one of the only items spawnable in-game that can’t be placed into a recycler at all.
As far as general appearance, two large glowing yellow eyes appear over the normal eye sockets of the player actively wearing them.