Is the double backstab / double one handed sneak damage a spell you can learn? I know some items, like Windshear, have effects that cannot be learned. Also, is there a difference between those two spell effects? I was curious about the difference in wording.
1. As previously said, learning an enchantment destroys the item.
2. You cannot learn enchantments from unique items - such as special armor, daerdric weapons, etc.
3. double sneak damage is not available to be learned (so you can only get it by wearing something that it has in the game)
4. At 100 you can double enchant, but you cannot add an enchantment to an already enchanted item, you must start from a base item and add them both at the same time
Hope this helps