depending on what the garrison commander says, a fixed blade knife may not be an option if he/she doesn’t allow it.
Truth be told. In my 22 years active duty, a good EDC has far more use.
I suggest something with a steel that is easy to sharpen. Many of today’s modern super steels are such a PITA to sharpen (especially on deployment) I wouldn’t recommend it.
This is a consideration. Since he's Artillery, he will likely be stationed at any number of installations more suited to maneuver units and likely less draconian on fixed blades. I was able to carry a 5" fixed blade in Texas (Fort Hood, Fort Bliss, Joint-Base San-Antonio). I was only able to carry a smaller 3-3.5" fixed blade at Joint Base Lewis-McCord; Fort Benning, and Fort Gordon, GA. Much depends on the Garrison Commander's policies and the actual Unit's policies; again, combat arms are much more lenient. I carried a fixed blade throughout my 30-year career, including some higher-echelon commands.
If you're considering a fixed blade, I wouldn't hesitate to recommend something like the ESEE 3. It will work around most knife-policies on the majority of installations, carries well under the ACU shirt, is not cumbersome, lies flat, and is easily accessible. Carbon steel maintenance was never a concern even in the jungles of South America.
A multitool is another good addition/consideration. I like the MUT, but it's a big multitool. I've reserved mine to my plate carrier here in Afghanistan. For belt-mounted, I like the Victorinox Spirit multitool. For pocket carry, I really like the Leatherman Wingman or Sidekick; excellent multitools for the price. The MUT is heavy duty and an excellent field multitool; any of them would be a great gift.
A pocket folder/EDC is kind of tough. My son met Ernie Emerson at the Blade Show when he was 12 years old and has been a fan of Emerson knives since. He's in a university ROTC program as a Freshmen in college right now, but joined the National Guard and went through Basic and AIT at Fort Benning (Enlisted Infantry). For his graduation gift, I gave him the Emerson Rangemaster Sheepdog folder along with the Sheepdog poem...he couldn't have been happier and I couldn't have been more proud. Congrats to both your and your son. Military service is a serious commitment and sacrifice and I wouldn't have traded those 30 years for anything...
ROCK6