I agree. I work a fair amount with vets, many having come back from the Iraq and Afghanistan. NONE of them wanted a big knife. Geared up, they told me that their total patrol gear hit about 80 - 100 pounds depending on where they were going and how long they would be out. A larger knife was out. A fixed knife was out (although they did see some that carried them) as it took up too much room and was too heavy.
All of them favored smaller folders (say, 3" blades) they could clip within easy reach of their dominate hand. Although they appreciated a good knife, they weren't knife guys and didn't know how to sharpen one well. So they weren't concerned with steel, brand, style, name or anything else besides bottom line utility.
I asked them and they all told me they like a medium folder with a serrated blade to cut strapping, cordage, cloth and open packages. Almost all carried a multitool with their folder.
Not one carried a large knife, not one carried anything that would be considered a zombie killer or other such nonsense. Not one had any ideas of being in knife fight. The place for a fighting knife was taken up by an additional clip of ammo.
Ask your buddy what he wants. Ask other vets.
Godspeed to your friend and I hope he has a safe rotation.
Robert