Soulfinder
Associated with Thoth, Soulfinder was a relic crafted by Proteus in ancient times. Resembling something between a dagger and a dirk, in the hands of adventurers it allowed its user to store a bit of people's souls, after which they can be easily located. It had a well-honed steel-grey blade, a simple cross-guard, and a pommel that ended with a small, rounded cap; otherwise, it is not a very fearsome-looking weapon.
Soulfinder passed through many hands after its discovery in the Modern Age. Ushering in the Age of Woe, Pazuzu took up the knife along with his arsenal of Protean weapons before he relinquished it to Khalas to solidify their triumvir arrangement. In the wake of a successful pantheonic strategem to injure the Wanderer God, a vengeful Han-Silnar secretly took up the relic from the battered deity and slew Him with it. Han-Tolneth was its last bearer. The soulful dagger's timeworn steel was shattered in the maiming of the Soulbleed Nexus in 924.