Rending Slash info

Sunah

So im reading many different things from many different people and im here now hoping for some clarification if possible. I have been told by many sources that Rending slashes procs your Off hand enchant. While testing some stuff on the dummies ive noticed that this is in fact false, while yes it does have a "chance" to proc your off hand enchant but based on what ive been reading its suppose to be a 100% chance... Can anyone clarify this for me?