Demonium
Sometimes called cursed metal or unholy alloy, demonium was a twisted black metal that was always chilling to touch. It was a supernatural material, used by Demons and their minions. In the hands of a Demon, demonium took on a silvery luster.
Demonium was the Ultimate Evil's attempt to recreate the holy metal given to angels by The Creator. No other entity was able to create the Holy Alloy, and demonium became a powerful but objectively inferior copy.
Working demonium required profane knowledge that could only be acquired through the cooperation of a Demon. Things forged from demonium were extremely powerful, but invited grave trouble.
Mortals that wielded demonium weapons or tools, donned demonium armour, or held onto demonium trinkets found themselves contributing to the Ultimate Evil's plans and often couldn't help but find themselves serving the Evil One's will. Demonium was designed to help facilitate long-distance (even interdimensional) communication between demons, and so the voice of the Ultimate Evil could be heard by mortals that touched such objects. The Evil One's whispers snaked into the heads of whoever held demonium for long enough. Even demonium scraps of chainmail from slain Demons had a terrible corrupting power.
Being within proximity of demonium items for prolonged periods of time amplified negative emotions and evil desires. Good men could turn cruel, and kind women could be filled with indifference or greed. Arcane casters or those interested in magic could be easily swayed towards the path of the profane.
Following the Demon Wars, demonium in any form was collected by the Cornerstone Foundation for safekeeping away from the public. The Righteous Order would succeed the CF by securing such items within the Righteous Fort's Repository.