Quote Originally Posted by Shaofoo View Post
Quite frankly just copy the effect of the Ioun Stone of Strength.

Gauntlets of Ogre Power - Your Strength Score is increased by 2 up to a max of 20 while you are wearing the gauntlets.

It might not be unique but it is sure much more balanced. Nothing says that you can't have the 3.x version of stat items in your 5e games complete with restrictions to obey the stat cap as well. You can have the belts just give higher bonuses and even some breaking the stat barrier but not beyond 23 (So we don't step on a Barbarian's toes)
How about:

Sets your Str 19. If your natural Str is 19+, it adds +2 str.

Some benefit to high str characters, same benefit to low str characters, functionally different from other magical items, and simple.