A trained person can strike with a knife quicker than they can shoot with a drawn weapon. If you have to actually draw a weapon from a retention holster, you have no chance against someone with a knife or blunt weapon under 20 feet away. There are few good options for dealing with someone having their hand on a concealed gun or knife, except have more than 1 officer there so they're not quite as confident they can kill you without being killed. People question why someone got shot 20 or 30 times