I want to enchant my Blades Sword with a shock damage enchantment but my enchantment skill isnt that high.I was wondering if there is a way to disenchant it later and enchant it agian wiht a more powerfull spell.
No. It'll be destroyed. Once you make an enchanted item it's permanent, and besides that you can't disenchant the same effect twice. Get a blade with paralyze, disenchant to learn paralyze, and enchant a mace with it. That mace can't be disenchanted again because you already know paralyze.
Even if you could, disenchanted items are consumed in the process. So if you really want the blade's sword and can't get another one, I'd wait a bit to up your Enchant skill before slapping that shock on it. Or make fortify Enchanting potions. Or hell, both, then you get
really powerful effects.
Edit: What if...what if you enchanted a set of armor with fortify enchant, and then wore it, and then enchanted another armor with a more powerful fortify enchant, and then wore that armor, and then enchanted another armor with a more powerful fortify enchant...