Vorpal?
As in "The vorpal blade went snicker-snack, he left it dead, and with it's head, he went galumphing back..."
Part of my most faaave poem in the world, hehe.
Could also be used to describe the blade of an Axe...well you can see where I'm going with this...
Also if you design anything that looks uber evil you could always call it the "Varg".