Passage Keeper

This sentient artifact has served as the implement of the Reaper for eons. Whether death was the domain of a good, evil, or amoral god, the Reaper's job was to gather those souls that refused to pass on to the afterlife. While most souls quite naturally follow the proper flow of the universe out to their final destinations, powerful individuals can resist that pull. Wandering spirits would be gathered by the Reaper. In time, the identity of the Reaper became ingrained into the implement itself and the wielder became the tool.
As the deities of death fluctuated, so too did the purpose of Passage Keeper. When good gods ruled the dead, Passage Keeper's servant would gather wraiths, banshees, and poltergeists from the world and lay them to rest. When evil gods reigned, Passage Keeper ensure those of valor would find their peace whether they were finished on their crusade or not. As Passage Keeper worked, it grew stronger by gather motes of souls, the spark of life, and sentience. The will of the artifact bent away from service of a shifting superior and to itself. Passage Keeper began to grant shadows of its power to more than one tool (servant) at a time in exchange for their marked foes.

A climactic moment in Passage Keeper's existence is recounted in the story Pursuit of Passage Keeper 
Legend Lore: Passage Keeper serves as a more "by-the-book" patron for Hexblade warlocks in D&D 5e. While the subclass can be used as a mechanical base for a plethora of character ideas, Passage Keeper fits into the core Hexblade lore if that is desired by a player.