The lunar staff is a magic weapon and piece of lunar equipment. It is created during the Lunar Diplomacy, so 65 Magic is required to obtain lunar staff. Despite the quest requirement of 65 Magic, the staff itself has the stats of a level 50 weapon and does not seem to have any actual requirements to wield.
During the quest, it is made by using a dramen staff on the air, fire, water, and earth altars (in that order). Once the quest has been completed, the staff can no longer be created this way, but must instead be purchased from the Oneiromancer for 30,000 coins. The staff cannot be purchased if players already have one in their possession. The Oneiromancer has a fixed sequence in selling the Lunar equipment, and the staff is the first one on sale.
Players can make more than one staff during the Lunar Diplomacy quest. However, they will need a small collection of dramen staves from Lost City and enchant them all during the quest. After the quest, this is no longer possible.
The headpiece for the staff appears to resemble the Greek Caduceus, or the twisted serpents, which is the familiar symbol of the Greek god of thievery, Hermes.