The player holding the Moonlight at sunset
Moonlight is a weapon added by Better Dungeons. Moonlight cannot be crafted, but is a drop from the Goblin Boss. Moonlight offers a Resistance buff when using its right-click ability, which ends as soon as the player releases right-click. It can be repaired on an anvil with iron ingots.
If you don't have a Giant Sword or Shield to block with, Moonlight can be an adequate alternative. This blocking effect doesn't seem to lower the durability of the Moonlight.
The right click abilitiy (blocking) in effect. Notice the Resistance icon on the screen.