The Shield is an item in LameDuke.
The Shield can be picked up, but there is no way to enable it. Based on its name, it would either behave similarly to the final's Armor or absorb every attack until something would happen to it.
The Shield can be found in hidden areas in levels (such as in the vent across from where the player starts E1L1 or in a blown-in hole at the RPG building in E4L1), suggesting that it was supposed to be a rare item that could only be found by exploring.
The Shield was completely removed in the final game, but the idea of an item reducing the amount of damage you take lived on in the Armor item.