Sorry I am getting in on this so late, but I think I might have some info to contribute (even though the OP is likely done with Basic/Boot). There is going to be A LOT of restrictions clambering to tell you what you're allowed to carry when it comes to knives. I have never read anything in the Army regulations that prescribe what you are permitted to own/carry. But post policy, company/battalion commander's policy, and what your platoon sergeant will let you get away with will all determine what you can carry ON DUTY. The moment you step off the federal reserve all of those protections/limitations effectually go away and state laws take over.
For anecdote: I carried a fixed blade in direct conflict with post policy in one place because my company and platoon sergeant didn't care and off post I was still legal by state law. In another place I carried an even larger fixed blade because post policy allowed it, company didn't care, but off post the state didn't allow for the carry of any fixed blades at all. Knowing all of this, it should be recognized that A LOT of posts and states that prohibit autos of all kinds. I think that, because of this, a lot of commanders and platoon sergeants don't want their guys carrying autos. Whether or not they believe them to be more dangerous, they don't want their subordinates arrested for carrying an illegal knife.
You'll hear this a lot, but as long as you use your head and are situationally aware, you'll be fine. Don't show up to a school or new unit carrying an OTF blade unless it it is written in black and white and published that they want you to carry one, get there and feel it out before you pull out your Benchmade auto. I sutured a guys hand on his FIRST day at one unite because the idiot showed up with an OTF knife and his buddy stabbed him with it. No joke. The guy never lived it down.