The Moonset has a short, blue-grey handle with a white spike set in its pommel. Its guard is comprised by two red spikes that angle downward. The base of the blade is a black diamond with a black spike resembling those on the Nobody logo on either side. These spikes point diagonally upward. The shaft is gold and forks into a “Y” shape halfway up its length. The tip of the blade has is shaped like a spike on the Nobody symbol. It is black and has red edges.
When Saïx enters his berserker state, both the tip and shaft of the blade become longer and change shape slightly. The two spikes at its base also become larger, and the weapon gains four more similar spikes, two on each side. These new spikes are white and have red edges. The similarly named Moonrise is identical to the Moonset, save for its color.
The name is a term for the moon disappearing from the sky in the morning (much like the sun disappearing at night is a "sunset"). Moonrise, another claymore, has a similar name.
Moonset’s normal ground combo starts with an upward diagonal slash, followed by a downward diagonal slash. This move is then repeated before the final move of the combo is executed, which is a forward dash followed by a slow 360° spinning slash. The combo can be activated after the third attack, and consists of an upward diagonal slash, followed by a leap and a powerful downward diagonal slash after a short pause.
The aerial combo consists of an upward diagonal slash, followed by a more powerful downward diagonal slash after a short pause.
 See also