I have often found that when someone says, "Are you saying A or B" then the person they are responding to said neither A nor B.
But to simplify-
1. You can do what you want. That's kind of the raison d'etre of D&D. Get rid of the monk class. Give them magic weapons. Whatever.
2. If you're into theorycrafting, and focus on DPR, and don't pay much attention to the monk's other abilities, I'm not sure that a straight up monk class is what you're looking for. So it's kind of a moot conversation.
3. I pointed you to an example of an already written "monk" magic item- Insignia of the Claws, from HoTDQ. You might want to start there before theorycrafting your own. Unless you want an actual weapon, in which case any (simple) magic weapon works (albeit not with unarmed attacks).
4. Personally, I think that since the monk gains ki-empowered strikes, it's kind of a neat feature that the Monk doesn't need magic weapons. After all, while Olaf the Often-Drunk Fighter is Blathering on about his beloved Stormbringer, your monk is mocking him. YMMV.