From my time in the Army (I was in the Infantry but I stayed in the US the whole time, I was just a regular guy not a high speed internet operator sorry to say) I would say that you should just focus on getting through basic training first. If you make it, then wait until you get to your unit. They will tell you what you can have, despite what your recruiter said (in fact, dont trust your recruiter at all!).
Just get a good pocket knife, like a Swiss Army knife honestly. It wont get stolen, and it is more useful. Your buddies wont mercilessly roast you for your Rambo knife either. A big heavy dagger is a pain in the butt to carry, will slice you open while you try to open your MRE, wont cut as well as a good pocket knife (or have nifty little prying tools like a SAK), and will add to your almost inevitable future knee damage if you carry that useless weight around on top of all the other useless weight the Marines will make you carry. It will just take up space that would be better used. Even if you found yourself in a World War 3 action movie situation (you wont) then you would curse the big stupid dagger for taking up space and weight that could be used for water (the most important thing to carry) and ammo (also important I hear).
Just buy a Swiss Army knife. The military is mostly just sitting around and dealing with insufferable BS for a tiny paycheck and future disabilty pay from the VA. You wont be stabbing anyone (except maybe yourself if you use a giant double edged dagger for things like prying, or anything really lol). I was worried about this kind of stuff before I joined the Army too, like if I could carry a personal sidearm from home in my future life as a high speed Ranger. I should have just worried about being able to do more pushups before Basic.
