Made from a "space age" Saturnite alloy in the Big Mountain Research and Development Center, cosmic knives were advertised to be super-sharp, all-purpose kitchen knives that wouldn't chip or dull. A surplus of these knives were shipped to the Sierra Madre casino kitchens in preparation for the Gala Event. Though lightweight and durable, they proved to be too sharp for their own good, able to cut a person's thumb off if they were careless, and even slice through cutting boards with no effort. Concerns were raised about the safety and necessity of having so many of these knives lying about, but Frederick Sinclair insisted that only the best equipment be used.
They were also found to have incredible heat retention, able to stay super-hot for hours after being heated over a stove. However, they are much more brittle when heated, and if left on an uninsulated surface, they would melt right through.
Following the Great War and prior to the events of Dead Money, many of these knives found their way into the hands of the ghost people who stalk the streets of the Villa, who use them as weapons against any unfortunate visitors.
Compared to the regular kitchen knife, the cosmic knife is longer, stained red with cloud residue, and does more damage. Using Abraxo cleaner, one can turn it into a clean cosmic knife. They glow purple before they are cleaned, most likely due to years of cloud exposure. The name "cosmic knife" is a brand name only, referring to the "space-age" Saturnite material it's made of, and not because it originates from outer space.