That's fine.Ones that aren't supernatural relative to the setting they take exist in.
But then magic items have to be mandatory and biased to warrior classes like the older editions.
Or some other variant rule or class bias philosophy to uphold the parameters of the game.
None of which is in the DMG or any 5e book.
Again it all comes down to the issue of 5e being designed requiring your DM to be a vet.