The rarity of Sign of the Netherfrost is Rare, and been equipped it takes a “Bundle” slot. At this moment the item is available for trade.
Sign of the Netherfrost is a skin for Viper. The skin was added to the game on November 29, 2017, it was created by Hunter.
Sign of the Netherfrost is currently one of the most popular skins, but it is rarely seen in the game due to its high price.