If your character needs to change their gear and you are reluctant to lose the upgrade level already obtained you can transfer the upgrade to the new item. To do this you will need to collect a number of resources and find an armory. You need resources to transfer the upgrade without any losses. If you do not want to spend, one upgrade level will be lost during the transfer. If you transfer an upgrade from a stronger item to a weaker one, it will be free to keep the level.
You can transfer the upgrades between different types of items. For example, from weapons to armor.