sorry fellas, there have been some good points, but some of you guys are not really giving the best advice. while i admit freely that i have never been in theater and dont have first hand experience, i am pretty educated on military things and have quite a few friends who have been there and done it. the most recent of my friends, a marine infantryman who saw combat clued me in to a bit of "truths". bayonets and the like are tossed aside and never carried, most choose to carry large blades that are used more as tools rather than just cutters. he carried a strider mt and used it regulary to pry open doors and windows in addition to cutting and chopping tasks. this is what he said he used the most. while this is a bit pricey and obviously is not an option considering the budget, there are many that would fit in your plan. try the buck strider fixed blade knives, they carry the same warranty and fit the bill nicely. TOPS and Becker are always favorites as well. if the pocket book can afford more, of course i would reccommend busse, strider, jones brothers entry tool, to name a few.
so i guess the next question that you need to ask is what is he going to be doing there. if its infantry, or front line assault work, they do mostly policing and patrol and do tons of entry. this also brings up another option, mini axes, pry tools and the like are one thing my buddy would have liked to have had on hand. a folder and a multi tool will definitely see use, but im getting the impression that you want to get him something with a bit more heft. hope this helps.