Adding existing enchantment to existing item

[swk3000]

Here's what I want to do. I want to take the Psijic Robes, give them the same enchantment as the 'Master Robes of Destruction', and place them in the safe in the Archmage's Quarters in the College of Winterhold, along with unenchanted versions of the Psijic Gloves, Boots, and Hood that I can enchant myself.. I don't doubt that this is possible (and quite easy), but this is literally my first attempt at a mod, and none of the videos or tutorials I'm seeing are showing me how to give an existing enchantment to an existing item; they mostly seem concerned with adding a spell effect to an item. How would I go about doing this? Also, for minimal impact, I'm wanting to mess with the Psijic Robes, but leave the Master Robes of Destruction as they are in the base game.