I had a bad incident with the USPS where I was shipped 2 knives, one of the knives was lost in transit and the other damaged to the point it was unusable. When I filed a claim I was rejected on the grounds the parcel contained "restricted items" even though the packing was clearly labeled. If you use the USPS I would recommend signature upon delivery and should you suspect your knife has been damaged, refuse the package. Insurance is probably only going to do any good should the package get lost.
8.3 Restricted Matter
Restricted matter is an article or substance prohibited or limited by title 18 of the U.S. Code. It also includes matter not otherwise restricted by 18 USC 1716(a) because it may, under conditions encountered in the mail, be injurious to life, health, or property. Examples of the type of restricted matter content moved to Publication 52, chapter 4, include:
- Intoxicating liquors.
- Firearms.
- Knives and sharp instruments.
- Liquids, powders and odor-producing materials.
- Motor vehicle master keys and locksmithing devices.
- Controlled substances and drugs.
- Unsolicited promotional samples.
- Instruments for use in animal fighting ventures.
- Cigarettes and smokeless tobacco.