The Hooked Shortspear can be found in Out of the Abyss, page 224.
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.
On a hit with this weapon, the wielder can forgo dealing damage and attempt to trip the target, in which case the target must succeed on a Strength saving throw or fall prone. The DC is 8 + the wielder's Strength modifier + the wielder's proficiency bonus.
A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.