The ritual knife is used by the Swampfolk in rituals. It 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.
Toy knifePoint Lookout (add-on) - Using even less AP than the ritual knife (10 instead of 12) the toy knife uses the lowest amount of AP for any weapon in Fallout 3. However, it does very little damage, much less than the regular knife.
One of Jaime's holotapes found in the Dunwich building speaks of a "sharp knife" used to "send him to deep temple". It is not known whether the ritual knife has any connection to this statement.
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