Good thread, and well spotted Egg - it certainly has not been properly covered here.
Since you are preparing, there is some benefit in having a selection for different scenarios (domestic, camping, car bug out, on foot bug out etc). I think you need to cover all the bases which are, in no particular order:
1) Machete
2) Axe (s)
3) Small knife (s)
4) Big knife
5) Folding pocket knife (locking, if you laws allow it)
I am the proud owner of a Wilkinson Sword Dartmoor survival knife that I would be happy to be with if the SHTF, but its huge and heavy and impractical as your only knife (but you could get by). I also have a Hattori deer skinner that is a fine high quality blade.
I agree with Egg about Carbon blades, but you have to remember to look after them. I think a lot of bollocks is talked about blade steel, and there is a ton of good info about it on the web. Look out for VG-10, 154CM and D2 tool steel (aka carbon).
Also worth noting is that very few knives (except the really expensive hand finished ones) or tools for that matter are delivered properly "sharp".
You should purchase a sharpening system based on different grades of abrasive that ends up with the edge being highly polished. A blade that can easily sever the cells of the material you are cutting (be it wood, animal or vegetable) is what you should aim for. You should be able to shave with your Axe! It might sound silly, but buy a book on how to sharpen knives, read and learn and figure out how to do it properly. There is nothing like using sharp tools
It makes me almost as happy as using a well tuned chainsaw.
Finally - NEVER BE WITHOUT a good knife. Even if its a small pocket folding knife that is designed to conform to your local "carry" laws. Have one at all times.
Also remember, where you have a knife you must also always have a first aid kit.
Finally, dont even think of buying a combat knife unless you are planning on getting properly trained in fighting with a knife (which is hard training to come by these days). I wouldn't advise even thinking of using a knife for defense/offense unless you have at least three years of martial arts training first ("black belt" standard -though what that means these days is anyones guess, the standards seem to have slipped)
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