The DC handgun ban is not any better then enforcing a gun ban. It is in my opinion that there should not be any gun ban in place. Reason being because it would not solve any problem. Criminals are going to still carry a firearm, whether it be a handgun or not.
Disarming people means very little. Sure, you get guns off the street, but there's absolutely no prevention going on and preventative measures in situations like this would probably be a lot more appropriate. The only way I can see disarming as a viable option is if there is some incentive for the disarming, like a gun buyback.