I was thinking... what if attunement itself was the mechanic for a returning weapon?I would just add it to +1,+2,+3/uncommon, rare, very rare) with added attunement requirement.
Same for instant return throwing weapons.
Lots of people try to avoid picking up attunement items because of the 3-item limit, but what if an attuned item was more closely bound to you? What if an attuned item could not be removed/pick-pocketed, because it comes right back to you the moment it leaves your reach? You would have to unattune it, or it would have to be dispelled temporarily, for the item to be removed from you.
If the item leaves your body against your will, the moment it is out of your reach it teleports back to where it was, the slot it is worn in, or your hand.
Items that are willingly thrown or removed, can be called back with a thought (no action). This opens up thrown or disarmed weapons coming right back to you, and attuned armor being able to be conjured to be worn.
Perhaps attuned projectile weapons make their own ammo when wielded for use. (Maybe that is too much.)