Vorpal is a word (almost invariably an adjective)
coined by Lewis Carroll for the poem
"Jabberwocky," used first in the line "He took his
vorpal sword in hand" and "One, two! One, two!
And through and through / The vorpal blade went
snicker-snack! / He left it dead, and with its head /
He went galumphing back." Vorpal is commonly
assumed to mean "deadly" or "sharp", and may
imply that the blade has magical properties. Many
role-playing games (beginning with Dungeons &
Dragons) have taken the latter interpretation and,
since the hero brings the dead Jabberwock's head
home in triumph, have used "vorpal" to identify
weapons with a magically enhanced ability to
behead enemies. It is also occasionally interpreted
as meaning the blade is warped.

Vorpal at wikipedia
What is a Vorpal?