Well, on the weapon distribution, I don't really like it. On an urban setting -more urban fantasy than modern with elves- sidearms are the simple weapons, weapons considered simple on standard fantasy become actually rare and exotic. A sickle? in the modern world that is a military weapon, a quarterstaff? I guess it would be a broom, a dagger? ok that one is actually more likely as a swiss knife. But crosbows and bows are fairly exotic, and expensive. Every class should have proficiency with at least the smaller weapons, not just the more martial ones. (And I didn't like that the sorcerers just don't get a chance to be proficient with them like wizards and clerics. It makes sense on druids though)
I don't know what to think about the aim action. There could be other ways to balance firearms.
On armor, it should be less differentiated, modern armor is designed to be as unobtrusive as possible, no need to "train with it" -except perhaps military grade and grenadier grade armor- And it is less covering than medieval armor, I don't see any reason for stealth disadvantages, it may make sense if it is just a reskin of medieval armor, but it doesn't feel like modern armor.