How do I know you haven’t made 10 copies of that same certificate and sold 9 to other people?

If it was an NFT I could see you issued 9 other copies of it before I was approached with the sale. Any other way I either have to place blind trust in you or rely on a 3rd party to handle the issuance/transaction

Yes but NFTs are held in trust by you, not a 3rd party business. If you want to sell your NFT to a friend you can do that without brokering the exchange through a middleman who can/will charge a cut

So brave

Are you going to bring your 3d printer into your university’s exam hall to write your final?