The toktz-xil-ek (also known as the obsidian knife or obsidian dagger) is a dagger-like weapon. It requires 60 Attack to wield. Unlike other daggers, this weapon has a higher slash attack bonus than its stab attack bonus. Additionally, this dagger cannot be poisoned. Players can buy the TokTz-Xil-Ek at the weapons store in Mor Ul Rek for 37,500 Tokkul. This weapon cannot be made using the Crafting and/or Smithing skills.

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.