Cairn Scythe is a weapon classification for magic items with the soul sucking property. The first of these weapons came about in Dawn Era as a means to get more souls into a particular Soul Gathering System. In the Dawn Era, the primary way of strengthening the energy of a system was to get more souls to come to it. This was before the Wells of Afterlife and before systems became magnets for certain alignments - soul gathering systems.
When it was learned that the demons were using soul sucking scythes to steal souls and take them back to the Abyss, others decided to get in on the action. The idea was copied and ended up being used by all alignments. Goodly wielders of a Cairn Scythe were naturally the most restricted since they could only take the soul of an evil creature. The sucked soul would then be drawn through the weapon, sometimes drained of some of its life energy, and then sent to a goodly system matching the weapon's alignment. The evil creature would then go through a process where they would be redeemed, becoming either neutral or good in alignment. On the other hand, evil wielders, and some neutrals, had no qualms about taking any alignment and feeding it back to their system. Near the end of the God Era, the gods agreed as part of the Rule of Divine Governance that all such weapons should be collected up and destroyed. This was impossible to enforce, resulting in many Cairn Scythes being left behind, scattered across the worlds of the mortals.
Cairn Scythes were purpose-built to strengthen the Soul Gathering System in which the weapon was tied to - with ones forged of Abyssal energies sending those killed to the Abyss or one of pure neutrality sending their victim's soul to Equipoise. After the God Era, an enterprising mortal necromancer got a hold of one of these weapons and fused it with necromantic energies. This resulted in a weapon with a vampiric hunger that instead of seeking blood, sought to feed on the souls. This practice has continued since that first weapon, with the result always being a very evil weapon. Soul devouring weapons are the most dreaded of the Cairn Scythes for those killed by them have their soul destroyed with only a wish capable of restoring it. Examples of true Cairn Scythes are Bleeberghast and Sanglamore while Sarquiness, Grarg, and the Helms of Molakh the more baleful types that utterly destroy souls.
Some Cairn Scythes, like the Bileddanul Slayer, act as conduits for souls where they are taken to a particular being where they are used as energy or simply consumed.