I just did m first overseas transaction and it went remarkably well. (Props to Ikkyo)
First and foremost, it pays to communicate everything clearly and in advance of the transaction.
Second, it's a good idea to lay out terms that are easy to abide by, and make sense.
You I'll have to pay more for shipping, and your buyer should know in advance that he/she will have to pay the fees.
You may not be able to do much for the buyer after the knife leaves the CONUS, and it would pay to let it be known up front that you will do what you can, but that once it leaves the CONUS, the knife belongs to the buyer.
Find out what you can about overseas shipping and tracking info. I used overseas express mail from the USPS, and was able to get insurance and a tracking number.
Speak to the buyer about customs forms and how you will value the knife. The buyer will most likely have to pay a tax on any product received from out of the country. You and he/she will have to decide whether you are comfortable lying on the customs form to keep his/her tax low. That is between you and the buyer, though I would suggest that you be honest for insurance issues, as well as because it's the right thing to do.
Lastly, again, communicate early and often. Let your buyer know the tracking info as soon as it ships, and let your buyer know to be patient. Sometimes, depending on the country, customs can take a while to clear a shipment.
Oh, and it behooves both you and the buyer to label the knife something nondespcript, like "camping tool," but again, decide that with the buyer.
If you follow some of these guideliness, you should have a hassle-free experience. I hope it works out well for you.
Regards,
Jason