Maybe I could interject some of my limited experience. I have served 3, one year tours. One in Afghanistan, and 2 in Iraq with the 2/325 82nd Airborne. In Afghanistan as well as in OIF 1, I saw some guys carring a pretty crazy aray of edged stuff. Hell I even saw a guy conducting raids in Balad with a sword on his back. I came back for OIF 3, and lets just say that the political environment had changed. Every officer had a hard on yelling at a guy with something out of the ordinary. Our company put out that no fixed blades over 7 inches would be authorized to be carried on personal equipment (with the exception of bayonets). I did then and now carry a satin Jack on my web gear as my general purpose knife.
Now out of a line unit and a Staff Sergeant I tend to be becoming sort of a scrouge with my men and their big knives. Frankly in the desert I don't find a whole lot of use for them. If their breaching a door, there are better tools. If their conducting some sort of emergency close quarters edge weapon combat, then it was my fault that they weren't trained correctly in how to use and retain their rifle, and that they would be in a situation where they were at such a tactical disadvantage.
With body armor, shoulder kev and side plates, a rifle, a combat load of ammo, water, and personal equipment, I have seen a many man fall out from heat exhaustion, nearing stroke. Frankly in area's where heat is so sever, I have enough to worry about taking care of my men, and insuring their training is top notch. Obviously I love knives. They are amazing tools, but limited. Especially in this environment. Just my humble opinion and my .02