Name that Sword!

I've got a long short story (or a short novella) appearing soon in an anthololgy called Blood and Devotion from Fantasist Enterprises. Outside of my Dragon Age books, it's my only short story about a dragon. In this case, the dragon is called Greatshadow; he's the exact literary opposite of my Dragon Age dragons. These, I built to obey the laws of physics and biology. Greatshadow, I designed to obey the laws of myth. He's a big, honking, six-limbed, fire-breathing beast with a wing-span a half mile across and a propensity for piling up large heaps of gold, silver, and jewels to nap on.

I'm currently writing a fantasy novel that expands on the short story, unfolding in this alternate reality where dragons breathe fire and wizards perform magic by telling lies to the universe and making the universe believe them. The big picture of the story is that the adventurers are on a quest to kill Greatshadow, the primal dragon of fire, a three-thousand year old beast that is more of an elemental force than a flesh and blood creature. The thing that makes killing the dragon possible is a magic sword. In the short story I'm basing the novel on, the sword is called "Frostbite." It's a blade of enchanted ice that's sort of kryptonite to a dragon of fire. My problem is, for the book, the name "Frostbite" seems overused. While I can't think of a specific instance, I'm pretty certain that in the 10,000 fantasy novels on the shelf already, someone has already used the name Frostbite for a magic sword.

I thought of calling it the "Winter Fang." But, I googled that, and sure enough, that's also already been used. In the book, the legend behind the sword is that it's been carved from the tooth of Hush, the dragon of ice, the opposite force to the dragon of fire. The sword is formed of a substance known as "false matter*," and is, essentially, a sword shaped vacuum of absolute zero that disintegrates any "true matter" it touches. I thought of calling it the Nulfang, but I don't like the look or sound of the word. And, other ideas I come up with all die beneath the crushing force of Google: I think I have something, but when I google it I find that some game or book already is using the name for a sword.

So, I though I'd throw it out to you guys. What would be a good name for a really, really cold magic weapon? It doesn't have to be a sword: I suppose the plot works just as well if it's a spear or an axe, but I'd like to keep it a hand-held weapon: the climax needs to have the hero within arms reach of the dragon, so, no holy handgrenades. Any ideas?

I don't want to turn this into a formal contest, but if you suggest a name and I use it in the book, you will, of course, wind up in the acknowledgements to the book, and get a free copy. However, since the book isn't written, and has no publisher lined up, it might be a while before that reward materializes; the non-existence of an prize is why I'm not making this an official contest. Just post your suggestions in the comments section. Feel free to make more than one suggestion.

*In this world, there are four essential forces that blend together to form reality: Matter, Spirit, Truth, and Lies. Most of the physical world - chairs, mountains, hammers, rain, and lollypops- are made of true matter. Dragons, according the the church, are made of false spirit matter. Most things are combinations of two of the forces; humans are the only things known to be made from all four forces, which either makes them the most balanced thing under the sun, or the most unstable.