Nicodaemus

I had a look in the files of the gamedata and it seems like the numbers should be: 4 damage DOT, ticking every 12s, for 60 seconds. Each hit adds a stack to the DOT. Both of the upgrades have a 10% chance per DOT tick of occurring.

If you use the dual wield spiritual weapons - Magran Sword/Pistol and Skaen Club/Stiletto - The lash 50% bonus will only work on the main hand weapon, when attacking normally or with a Full Attack.