GP knives is G2G, nothing fishy going on there, just protecting you as the card holder. Your in Europe you said right? That's very common practice and shouldn't be much, if any inconvenience. Again it's just a small step, almost no hassle to protect you as a customer and a card holder.
Yeah, I worked it out with them.
I did some more reading on international orders with other stores, and it seems like most have some sort of additional rules for this.
BladeHQ requires you to e-mail them (Will they ask you to provide some ID? I don't know.), and has a list of stuff they won't send. (The only item that, I think, should not be on there, or at least up for discussion, is the machete. The rest of the items would most likely cause some trouble with the customs.).
NewGraham requires your first order to be through Western Union.
Knifeworks requires you to send them a copy of the credit card (Not sure what this means - maybe a picture?). Knifeworks also won't send swords because of the cost of shipping, but shouldn't that be up to the buyer?
Knifecenter and Knifesupply seem to be two of the few that accepts Paypal and ships internationally with no additional rules at the moment. However, while Knifecenter has a lot of models, it seems like the majority of their stuff is out of stock. Maybe this is related to the holidays, and they are restocking. Their prices also seem to be slightly higher than some of the other stores. The times I've ordered from Knifecenter, I've usually received the package after 3-4 days. (I live in Norway.).
Knifesupply has a decent selection, but their customer service isn't that great, or is very busy, and they don't list the stock status - so, I wonder if they order the stuff you've ordered from another supplier for the majority of their stuff. They seem to have relatively good prices though.
Experience with shipping internationally is, however, also somewhat important (For international buyers, of course.) - for Norway, at least; if a package doesn't have the right documents and invoices, the package will stay at the customs office until they have it. This means that, either you contact them with the correct information (Sending an e-mail with social security number and the order information.), or wait for a letter from them (Which asks for the necessary information, or authorization to open the package, presumably so they can value the contents.).
I had to contact or provide information for the customs office for the last 2 packages I received -- one was from Lamnia.fi (Had to provide social security number.), the other was from Knifesupply.com (Had to provide commercial invoice, social security number.).