Because I know I always search for threads about obscure weapon effects..

On Sed-Zik, the Water-change (Jidz Tetka in Water Stance)--

The Dexterity damage and Paralysis effect are rolled separately--(You can save vs. paralysis but fail save vs. dexterity damage) Both are poison typed effects, and do not work against creatures immune to poison.
http://ddowiki.com/images/Thri_keen_venom2.jpg (Shot of an ogre saving vs paralysis but failing vs dexterity damage)

It can hit for more than 1d6 dexterity damage.
http://ddowiki.com/images/Thri_keen_venom.jpg
(EDIT: It seems like it actually does hit for 1d6 dex damage, but the 1d6 damage is affected by the 50% increased damage from the paralysis effect which causes helplessness. The paralysis effect is rolled against first, so if you do get paralysis off your dexterity damage will be +50% higher if it lands)