It is a possible enchantment. Out of my 5 characters I made, I've only seen one, while I was dungeon dwelving at around 45~. Not saying this is the level you have to be, but it may be that you have to be high leveled to have a chance of finding one. The only guarantee'd weapon that I can think of that has this enchantment is Chillrend, which can't be disenchanted, but it has a pretty good base value and can be improved to be on par with some of your other weapons. Not sure if you know this or not, but paralysis in Skyrim isn't a 100% occuring effect. In other words, your enchantment might look like this. Chance of paralyzing the target for X seconds A chance is better than no chance at all, but at high levels, I find it easier to just tear everything with regular weapons.