It has been my experience (examining the bayonets that arrived with my mil-surp rifles ... mostly Mausers, although I've seen others Garand, CETME, etc) that they are designed for thrusting and prying and not for cutting. Metallurgically speaking, this optimization will mean heat treating and then tempering them to a lower hardness and higher toughness (they don't really need to hold a razor sharp edge, but you CAN'T have them break in use). From a knife design perspective, that same optimization will lead to thicker cross sections and steeper grind angles leading toward the edge. What this translates into is a blade profile that, even if it hald a razor sharp edge, would slice very inefficiently. It might make good shallow cuts, but then the thickness would quickly get in the way.
I think that the Finnish Pukka bayonets were the exception, but these are VERY rare and quite expensive IF you could find one. I would recommend that you just save your pennies and get a good quality knife from reputable maker. I make my own so I get to determine both the blade geometry and the hardness, but if I were to buy one today, I'd look seriously at the SOG Northwest Ranger or Field Pup (although I'd prefer less toughness and a harder steel than these have). In general, I'd stay away from designs that purport to be unbreakable (that's why we use crow bars when we need to pry something) and I would lean towards flat grind profiles instead of the hollow ground that seems to accompany the KaBar and Bowie style of knives. The design of the Fallkniven F1 is very close to what I have settled on as the perfect all purpose fixed blade. I don't know about their heat treatment, but they use good quality steel in that one ... might be more $$$ than you want to spend, though.
Hope this helps.
Saands
