Thus far, the Army has given me no knife training, no defense against a knife, no offensive use, unless you count the bayonet training I did in basic training. Stab series, that sort of thing. I don't count that. As for what I carry, I carry a TOPS Knives Swat Spike on my Interceptor Body Armor. It is simple to sharpen, made out of 1095 carbon steel. It is a one piece, with two linen micarta scales for handles, and it has a chisel butt end, which I can use for prying stuff open. The knife itself is pretty thick, so I can pry stuff open with it. I have used it to cut various items, no people, mostly just MRE's. But, it is always available if I need it, in a spot that I can access with either hand. All in all, I like it a lot.
When I am out on an extended operation, where I expect to run into some serious trouble, I also carry a Cold Steel OSS on my right leg. I do not feel that the OSS is quite as durable, but it sharpens up to a shaving sharp edge easier, and it had greater reach, plus being twin edged makes it the ideal "go to" knife for me, before my swat spike. Also, on extended operations, I like to have two knifes, just in case...
Kent