I agree in having silenced weapons, you will have the ability to kill a person without having to trigger the alarm, unless you alienate other people.. the drawback in this is that it will have less piercing damage, and trying to kill a guy with Armour with a silenced pistol, that would be ineffective, unless you get the choice were to aim. As well as the sound produced and I believe the sound produced should be at least 2-3 squares away or behind a wall if you are adjacent to one with an entrance behind you. But the question is how would you know if there are people nearby, can we add the system that you know were the enemies are (Security cameras upgrade) when you get raided, with FoW to make it fair?
I do not how you would go about with blunt damage but that's your choice.. Back to the subject, this brings me to another idea with sneak attack and stuff, as well if you add silenced pistols and guns. It's the aim toggle, when you decide to shoot a guy (or stab him in the back) you get the choice were you want to aim whether its the head (instant kill), the leg (paralyzing), the torso(damage/instant kill), or well I think everybody knows were I'm hinting at as another choice. These are of course limited by your skill in the weapon used, and the damage dealt is dependent on the weapon and if its silenced.
The ability to choose were you want to aim would be very annoying when fighting in normal combat, I believe its best you get to choose (in an options menu or something) whether you want the aim choice in stealth combat, normal combat or both.