The rarity of Compendium Arms of the Onyx Crucible is Rare, and been equipped it takes a “Bundle” slot. At this moment the item is available for trade.
Compendium Arms of the Onyx Crucible is a skin for Legion Commander. The skin was added to the game on January 21, 2015, it was created by motenai.
Compendium Arms of the Onyx Crucible has been recently added to the game, which makes it rather popular with the game community.