And a ore in the end called chromium or enderium does uprade your gear for limited time, like making the protection 3 upgrade of a chestplate 4, even 5!
But, if you apply it so much like more than 2, it should have a chance breaking, losing high durability or its enchants

For example, I would separate enchants and upgrades. Upgrading table should be easy to obtain, like a crafting recipe of wood, stone and iron. When you put your item in it (example: diamond axe) it should show you the upgrades such as efficiency, unbreaking, mending, sharpness; every upgrade has 3 levels and costs xp and material (diamond)
And enchants should be unique, like fire aspect, smite, channeling, fortune, silk touch. They should be accessible from enchanted books and tables as same. The villager trade should go in level 3 or 4 to buy books