Here's the way I see it and I've been a hunter since the beta. Hunters are the wanderer class that is usually the lone wolf. You would associate that with snipers yes? You a snipe the big targets down from a range and run in to finish off small enemies like dregs right? If a hunter isn't going to use their knife the next best option is a hand cannon for close to mid range encounters. I mean one of our supers is you whip out a golden hand cannon with 3 shots in it (4 with aclyophage). At the end of the day I associate hunters with precision weapons and it doesn't get more precise than hand cannons and snipers. I'd give warlocks scouts, pulses, and fusions because they're a mid range class and obviously that leaves Titans with autos and shotguns because they're in the thick of the battle. Sidearms were never intended for guardian usage. They were for the queen's guard, but guardians were introduced to them in HoW.