These items don't really have nonsensical properties since they're cursed items where the curse is something that relates to primary function of the magic items (i.e. the shield of missile attraction gives you resistance to ranged weapon attack damage but also causes ranged weapon attacks against any creatures within 10 feet to hit you instead). The curse effects are also fairly simple and make in-universe sense in a way that some of the convoluted patch 7 magic items aren't.
Compare the effects of the shield of missile attraction to something like "The Jolty Vest" or "The Speedy Lightfeet" and you'll see a pretty massive difference in how the magic items are designed. The former is an item that can conceivably make sense in-universe while the latter two items don't, are far too convoluted, and just don't feel like items in any edition of DnD with their weird conditional (status effect) requirements that feel artificial and "gamey".
If Larian wants to have items that become more powerful when used in a set, they should look at how BG2 handled it with the Hammer of Thunderbolts.
https://baldursgate.fandom.com/wiki/Hammer_of_Thunderbolts"Alone, the Hammer of Thunderbolts is a powerful magical weapon but when merged with the gauntlets of ogre power and a girdle of giant strength the hammer is transformed. This transformation requires magical assistance. The Hammer of Thunderbolts is then capable of doing an additional +8 damage as well as instantly killing any giant or ogre that it strikes. "
The hammer gets stronger when used with the other specific relics but it's not completely useless without them either. It also doesn't generate "lightning charges" or "momentum" or any other weird purely mechanical status effects that make no sense in-universe. These sort of "set items" should also be rare as the vast majority of magic items should be standalone and should not require any other magic items to actually function.
