Crysknife



A crysknife was a knife whose blade was made from the tooth of a dead sandworm of Arrakis. It was the weapon of choice for the Fremen, the natives of Arrakis. It was a curved and double-edged like a kindjal, and 20 centimeters long, milky white in color and iridescent, and had a black handle with deep finger ridges separated from the blade by a slim round ring instead of a shearing-guard. The tip of a crysknife was also commonly poisoned, with an unnamed poison residing where the nerve of the tooth used to be. This poison is quick-acting and powerful as shown with the killing of the Laza tigers by Leto II and Ghanima.

Crysknives usually came in two forms:
 * Unfixed: Knives where the blade would disintegrate unless they were kept close to a human body's electrical field,
 * Fixed: Knives that had been treated so that they would not disintegrate, and could be put into storage.

To the Fremen, the crysknife was sacred, and they maintained much tradition around it. If it was drawn, it could not be resheathed until it had drawn blood. Moreover, the blade was not allowed to be seen by those considered to be outsiders by the tribe; otherwise they would have to die by it, or be "cleansed" in an elaborate ritual.

The sharpness of a crysknife was unparalleled. It was usually perceived to glow with a faint light. They averaged 20 cm in length.

Blades were considered a necessity on Arrakis. This was because neither shields nor Lasguns could be used in the Arrakis desert, due to the Holtzman field attracting sandworms.

Behind the scenes
In Dune: House Atreides "fixing a crysknife" is explained as "keyed to the body of the owner so it would dissolve upon his death" which contradicts the above definition.

Trivia

 * The "crys-" part of the term might be a reference to the crystallic structures of a sandworm's "tooth". These are not like the typical teeth of vertebrates, and are more comparable to a single strand of the baleen structures in the mouth of a filter-feeding baleen whale. Like the baleen strands, they are keratinous, horn-like in origin, rather than a true bony structure.
 * A similarly named real bladed weapon is the assymetrical kris dagger of Javanese origin, historically used mainly by Malay people in modern day Indonesia and Malaysia, and more rarely in other parts of southeast Asia. Aside from the vague similarity of the name, it is an entirely different style of fighting knife compared to the fictional Fremen crysknife. It's unclear whether Frank Herbert invented the fictional name as something of an in-joke nod to the historical dagger, or if it's just a coincidence.
 * The computer game Spelunky references the Crysknife by adding it as a ingame powerup, found in the Worm level, the worm's design being a reference to Dune as well.

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