What constitutes valid proof of shipping/delivery? If you're the buyer in Europe, and never get your knife, but the seller says "Well, I shipped it", what would you want to see as proof? or stated another way: as a seller, how do you protect yourself against a fraudulent claim of non-delivery?
The Tracking Number should be proof enough I think.
It is also in the interest of the shipping company to track the shipment to protect against a fraudulent claim if you insure the knive for whatever value.