The Tzhaar-ket-em (also known as the obsidian mace) is a one-handed weapon comparable to a mace, although unlike most maces it does not give a prayer bonus and cannot stab; it uses only crushing attack styles as it has no spikes. An Attack level of 60 is required to wield it. It is stronger and more accurate than the dragon mace, but it lacks any special attack.

When a Berserker necklace is equipped, this weapon gains a 20% damage boost. It is also affected by the Obsidian armour (helmet, platebody and platelegs) which will increase the melee attack and melee strength by 10%. The damage bonus does stack with the Berserker necklace.

Unlike other obsidian weapons, Tzhaar-ket-em can only be obtained from TzHaar-Hur-Tel’s Equipment Store.