xxGOGOxx is correct. My folder is far more often used for utility, and, while I acknowledge the likelihood of needing it for offhand defense is VERY VERY low, I never like ruling out options that may save my life. That said, it’s why I like drop points like the Presidio I mentioned, and I don’t pick knives with blades that are just “stabby” (for lack of a better term) or very specific to one function or for “fighting.” As mentioned, a good multi tool is EXTREMELY handy on patrol, for lots of reasons.
Another thought, as silly as it is, is uniform limitations. I’ve had many iterations of my agency issued uniforms over 15 years, and some have had pockets that were better (that is, unobstructed by duty belt items or of a particular opening size/pocket depth) than others. The shape and weight of the folded knife may affect how or where it can be carried with confidence. My Paramilitary 2, although a great knife, had to be forced in and out of the “knife pocket” in one particular brand of pants because of the overall height Of the closed knife. But it IS an all-around stellar knife choice.
Many of my coworkers are not knife people, and carry gas station specials or whatever they may have been given as swag at a training seminar. But if you ask this question on a knife forum, you gotta expect a lot of overthinking and minutia lol.
In short, get him any decent folding knife with a stainless blade (he’s gonna get wet at some point, be it rain, snow, sweat, whatever) and good lockup. There’s no need to go into the crazy money range, particularly for something that could be lost or damaged on the job. As your son, he will appreciate it, even if it doesn’t work for him in his work loadout. He’ll figure out what does, and still have a nice gift from his father to carry off duty.