The hilt of this dagger is shaped like a snake, and the twisted blade looks like an impossibly long tongue.

Created by cults that worship serpent deities, these +1 daggers are prized for their ability to secrete toxic venom. A viperblade has 5 charges, which are renewed each day at dawn. Spending 1 or more charges envenoms the blade (at no risk to you) for the next attack you make during this turn.
The poison deals 1d6 points of Constitution damage (both primary and secondary).
The save DC depends on the number of charges spent:
1 charge: Fortitude DC 12.
2 charges: Fortitude DC 15.
3 charges: Fortitude DC 18.

Prerequisites: Craft Magic Arms and Armor, poison.
Cost to Create: 3,000 gp (plus 302 gp for base item), 240 XP, 6 days.