I've been really lucky over the years. I have only had one item (1960s near mint Camillus Barlow) lost by the USPS. When I got the package, it was soaking wet in an envelope similar to what the OP received. The box was ripped at one and and the box was just full of balls of newspaper. Fortunately, I got my money back via fleabay's buyer's guarantee. The seller filed a claim w/ USPS, but I don't know how it turned out for him. The seller had just put the knife loose in with the wads of newspaper. If he had taped the knife to the box side before sealing, it would not have slid out through the hole torn in the wet box.
On the other hand, the number of lost knives could have been REALLY high. I have had NUMEROUS knives come in poorly secured. It's amazing how many idiots put a knife w/o a sheath in an ENVELOPE, with a little newspaper wrapped around it and expecting it to arrive safely. At least a couple of dozen times, a knife has shown up with the tip poking through the envelope or the box.