These are one of the most prized ancient weapons owned by the Space Wolves Chapter. Each was handcrafted by a Master Iron Priest and they utilise the diamond-sharp fangs of the Ice Kraken as the teeth for their chainsaw blades. A frost blade or axe is treated as a power weapon but adds +1 to the user's Strength.
Frost Blade or Frost Axe
Source: Codex: Space Wolves, p. 15