The Hooked Shortspear can be found in Out of the Abyss, page 224.
This weapon is decorated with dragon heads, claws, wings, scales, or Draconic letters. When it steeps in a dragon's hoard, it absorbs the energy of the dragon's breath weapon and deals damage of that type with its special properties.
Whenever you roll a 20 on your attack roll with this weapon, each creature of your choice within 5 feet of the target takes 5 damage of the type dealt by the dragon's breath weapon.
You gain a +2 bonus to attack and damage rolls made using the weapon. On a hit, the weapon deals an extra 2d6 damage of the type dealt by the dragon's breath weapon.
As an action, you can unleash a 30-foot cone of destructive energy from the weapon. Each creature in that area must make a DC 16 Dexterity saving throw, taking 8d6 damage of the type dealt by the dragon's breath weapon on a failed save, or half as much damage on a successful one. Once this action is used, it can't be used again until the next dawn.
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.