This would be much more versatile and useful than the system we have now. This way, no more "oh-noes-my-bow-has-a-fire-enchantment-that-is-useless-against-this-ancient-fire-dragon" moments, you could, mid-battle, change between various enchanted arrows.
Oh, and add arrow weight. It is just ridiculous to carry around 2000 iron arrows.
Another thing: You can destroy again itens with the same enchantment as you already know, so when you try to enchant an item with that specific enchantment, it will be stronger.
Yap, repost