[Pluto]

You can store it and wait until you reach the minimal level for it again.

Or, you can remove the enchantments at the forge(for the most part, that's inexpensive) and then reapply them later(the more expensive part).

So then when level 20 is restored, you can go back and reenhance the weapon back to its level? Thus having to use gold and xp again? Or could it be removed and stored and inserted again. Naturally a penalty in xp in gold to remove it but not reinstall it.