The Vice of Cain, also simply known as Vice or the Blade of Sin, is a bone weapon of an animal that was used by the first born son of Adam and Eve, Cain in order to murder his younger brother Abel. The weapon was fashioned out of the femur of an animal that Cain himself slaughtered in order to kill his brother out of jealousy and anger. It is said that as a further act of transgression, the animal itself was of Abel's flock.
After receiving the mark by Lucifer himself, the blade was somehow able to link itself to the mark. Later being said that his emotions were coursing towards the weapon. This in turn showed that the mark is able to curse not just a living being that is touched by Cain himself, but also an object. Since the bony weapon was the first used to commit an act of murder and sin, it is therefore considered to be the "root" of murder itself. This is evidenced from the fact that when Cain killed Abel, his blood spread out across the Earth and cursing the land itself from the horrendous deed like wheat in a field. Ironic since Cain himself is a farmer and the act is looked at as a farming of sin with the Vice as a cropping tool.
The Vice of Cain has since then been lost for eternity, and for good reason. For according to legend, it is said that any who so foolishly touch the blade will experience an intense escalation of negative emotions, specifically emotions like hatred, jealousy, and rage. These emotions are powered by the blade itself, and influence the wielder to carry out task of killing those that the emotions are focused on. Eventually, however, the wielder will die from prolonged use of the weapon for it not only powers negative emotions, it feeds off of them as well. Even from a certain distance one will find themselves being drawn to the blade.
The Vice of Cain is also virtually indestructible, as there are no conventional means of destroying it completely. Even divine beings such as deities and angels are incapable of fully destroying it. Even if it was shattered to pieces or reduced to dust, it will simply reform. According Gabriel, this is because that there is so much sin in the weapon that it's nearly impossible to clean as well as the fact that it is constantly feeding off of the sin that reeks in the air. He describes it has having to "drain the Earth's ocean with a tube". The only known beings who are capable of truly destroying are God, Death, and its original owner Cain.