Well, he didn't say he wanted Rangers, just a Ranger-trained personal guard, thats why I said yes without being picky.
If you wanted actual Rangers, I'd have to go find my copy of the first Ranger's Apprentice book and find the rest of what you need to be picked as a Ranger's Apprentice besides asking.
It seems that not only is six months not enough time and the rangers seem semi mythical so I don't think your guys will be as good as them but still the best this side of the whatever it is called generic landmark.
they are treated kinda semi-mythically, because if you stand completely still long enough while wearing camoflage, no one notices you
at all unless they're looking specifically for you, or until you move again, and then it looks like you just appeared out of that tree or bush, which freaks the heck out of most people.
also, yes, 2 years will get you some very good marksmen with some amount of knife skill, though you'll have to supply your own knives if you want that. I can't be spending extra money on knives for people who aren't going to be official Rangers when we have more necessary uses for our part of the castle budget, like getting a decent amount of Desert Camo cloaks made, and equipment for new apprentices.