I disagree - from what the OP has stated Reate is the manufacturer; but it was not a a Reate branded knife. "The maker and seller of the knives is in the US and that is where I sent the knife". It is that person/company that needs to deal with this.
M
MRC77
Stop dwelling on the insurance - it has nothing to do with this situation, whether it was purchased or not, because it is protection for the shipper (not the recipient). You can't make the claim, it is up to the shipper to fix this.
If it hasn't been done, the shipper should address the loss with the postal service. It was delivered, and they can figure out where. I don't know if you said when the mis-delivery happened; but an honest person would put it back into the system and it could still get to you. I've gotten several things over the years addressed to the house next door, and an occasional one for the corresponding address one road over. The neighbor's I just walk over, anything else close I drop off on my way home from work the next morning.
Assuming you had tracking, was it "Out For Delivery" from the correct post office? If so, it might be faster to make a visit and ask them to find out where it was delivered. Depending on the station, the counter staff might help... but you might have to take it up with the postmaster.