Hellfire Weapon

From Baldur's Gate: Descent into Avernus, page 223.

Description
Weapon (any), uncommon.

This weapon is fashioned from infernal iron and traced with veins of hellfire that shed dim light in a 5-foot-radius.

Any humanoid killed by an attack made with this weapon has its soul funneled into the River Styx, where it's reborn instantly as a lemure devil.