Dagger, Deep Sleep
This Dagger appears as a normal Dagger, a Detect Magic spell will reveal that it is a +1 Dagger.
Liber Mysterium
The Netbook of Witches and WarlocksBy Timothy S. Brannan and The Netbook of Witches and Warlocks Team
The true nature of this Dagger is revealed in combat. When ever and any time the Dagger scores a hit and causes at least 1 point of damage the victim must make a Will save (DC 15) or fall into a deep sleep similar to a Sleep spell. The sleep lasts for 2-5 rounds.
Caster Level: 5th ; Prerequisites: Craft Magical Arms and Armour, Sleep; Market Price: 5,000gp; Cost to Create: 4,000gp + 350 XP.