Yeah, I've bought quite a few things off fleabay too but why bother when you can get something from an authorized retailer where you never have to worry about a fake? I've bought hundreds of knives from dealers both online and brick and mortar and have never been sent a fake!
I'm a collector of a lot of things, not just knives, and I buy things on eBay because that's where I can find what I want/need, which is NOT limited to currently available items that are NOT available at online or rock/mortar retailers.
I've spent ten's of thousands of dollars on things on eBay, including but not limited to knives and I've had very few problems. When I did have a problem the seller and/or eBay always resolved the problem to my satisfaction.
For currently available retail items, including knives, I will do a price check all of the usual online sites for the item and will usually choose the cheapest site to buy that item. If the price is a push, give or take a few $'s, I'll almost always buy from the retailer and, even if it costs more than that, I may buy from Amazon because they offer can offer me 1-2 day delivery as a Prime member, if I'm in a rush to get the item.
It's a "free market" and a sensible buyer will check every source of an item they want to get the best price and terms that they can. Many of the best deals can be found on eBay and eBay's Buyer Protection policies make it safe to buy anything there.
Doesn't mean you can't have problems but proper examination of what is being sold from the photos/description and vetting of the seller before you buy is key to avoiding any such problems. If in doubt, you can message the seller to ask about the item and not buy it if there is the is an unsatisfactory response or no response at all, which is the same thing.
It doesn't seem that the OP did any of these things in this case but because of eBay's Buyer Protection policies he still should be able to get his $ back.