I've seen a Lan-Cay M9 bayonet that was so badly ground that the edge bevel angle was GREATER than 90 degrees.
The blades are thick, which makes them bad slicers. The steep grind exacerbates this problem, even when the edge angle is narrow enough to actually cut something.
From the semi-disassembled picture someone posted above, you can see that the "tang" is a narrow rod that runs through the handle. One additional twist is that the tang is not really of one piece with the blade, but SCREWS ONTO it. So, really, the blade is held onto the tang only by a few screw-threads of metal. My best guess as to why this inherently-weak design was chosen is that it creates a weak link that can break if too much lateral force is applied--the idea being, I'm guessing, to keep a soldier from damaging his rifle, maybe?
I mean, I guess almost ANYTHING vaguely narrow and pointy will work if you're trying to poke holes with it at the front end of a 5-to-8-pound rifle. I've seen what I'm told are SKS bayonets with flat tips that look more like a flat-headed screwdriver than anything else. And I guess if you've got a rifle's weight behind it, even a screwdriver head will penetrate most living things. But that's not to say that a screwdriver makes a good knife.
I'd say almost anything at all is better than an M-9 bayonet as a knife.
