Obsidian knife

The Obsidian knife is used during The Brink of Extinction. It is found on one of the scales in the first room of the tunnels encountered when chasing Ga'al-Xox.

The knife is used as part of a puzzle to open the door, along with an Obsidian sword and Obsidian mace. To open the door, the mace must be placed on the western pedestal and the sword on the eastern pedestal.