How would I make enchantments that modify attributes such as armor?

Hey there MCreator community! I'm a long-time user but I've never really delved into making enchantments with the software before. As I understand it, enchants that don't directly affect damage taken (similar to protection) need to be activated via global procedures. There's only one issue: I wanted to make an enchantment that is applicable to shields and gives the player extra armour points when held in their main-hand/off-hand, but I can't figure out a way to make it so. One solution I had was to modify the shield's attributes directly so that it simply gave armor when held in the main-hand/off-hand, but like I said before I can't figure out a way to do it.

Any help with this would be greatly appreciated!