The Spy-cicle is a replacement for the Spy's default knife that behaves similarly but with several interesting abilities.
Like Your Eternal Reward, the Spy-cicle performs silent backstabs, meaning that the backstabbed enemy does not make any noise. This weapon borrows a feature similar to the Golden Wrench, as well: backstabbed enemies turn to solid ice.
When the player is set on fire, the Spy-cicle's tertiary ability activates: the Spy-cicle melts but extinguishes the Spy and grants two seconds of fire immunity. The melted weapon operates on a recharge timer similar to Jarate or Mad Milk, reforming in 15 seconds.