Lily's gauntlet is an unarmed weapon sometimes used by Lily Bowen. Physically it appears to be a modified gardening glove, with additional reinforcements to the material as well as some form of padding wrapped over the knuckles.
This weapon is a companion-only weapon, and is marked as "not playable," meaning it is impossible for the player to obtain the weapon under normal circumstances.
Lily's gauntlet does not appear anywhere within Fallout: New Vegas, nor does Lily Bowen carry the weapon by default. However, the weapon is included in a list meant to track Lily's other companion weapons, Lily's assault carbine and Lily's Vertibird blade. This list is used by a script which periodically checks to ensure companions have not lost their specific weapons, and returns those weapons if they have. If triggered, this script will give all three weapons to Lily, including Lily's gauntlet.
pc You can obtain this weapon via console commands, however upon equipping it, it will not appear on screen, as though the player is unarmed, and the item itself will disappear in a matter of seconds from your inventory. [verified]