Ritual Knife

The  is a weapon added to Fallout 3 with the release of the Point Lookout add-on. It is used by the Swampfolk and can be repaired with Knives as well as the Slasher Knife and Ant's Sting. This weapon, along with the Atomic Pulverizer, has a high rate of attack and the second lowest AP cost in the game -- the lowest is the Toy Knife, but that weapon is less useful than the Ritual Knife due to its very low item HP, its lower damage and its lower critical hit multiplier.

The Ritual Knife is found in the caves beneath the Ritual Site, stuck in a skull on the sacrificing table near The Krivbeknih, after beginning the quest The Dark Heart of Blackhall (the cave's entrance is sealed until you start the quest).

Appearances
The appears in the Fallout 3 add-on Point Lookout.

Bugs
Sometimes the knife will have "sank" into the table or the body. It can be freed by explosives. Listen for the metallic clang to know if you have successfully freed the knife.