The best way to avoid getting killed is to make yourself scarce. Sometimes, that's not an option.
Rather than practicing your backhand on a bad guy who's reaching for something in his pocket, you really ought to joint-lock him with intent to incapacitate. If you have buddies around, they should make sure you don't get curbstomped by additional assailants while you're holding on to the perp. No matter what, gain control of the weapon as soon as possible so you can keep it from being used against you later; you can also use it to protect yourself from the aforementioned assailants, especially if you're alone.