"Cocked & locked" with gun in hand

I agree with gun out safety off. As far as weak hand goes, it should be center of chest awaiting the meeting of the manos however I'd disagree that it is helping fend off the assailant. If the off hand is allowed to move away from the body it presents potential problems. It can get into the line of fire being directed from a grip locked to the ribcage or it can be captured and used against you. If it is not going to become part of the grip, as when shooting from a retention position that precludes it, it should be held against the side of the neck. That position keeps it out of the line of fire and positions the arm so it can be a much better defensive tool. While the assailant is allowed a foot closer than a stiff arm allows there is also an extremely hard and unforgiving elbow pointed out to meet him. Lunging forward can drive the elbow violently into the assailant's torso. If the assailant is attacking with a knife the upper portion of the arm which can be struck while in this position has no major arteries or tendons which can be damaged. Above all else, practice and consistency of all training.