Well, there are two distinct things I can think about this post. First of all, if you are justified to shoot a person in a confrontation, don't let them get this close before engaging. Second, if you aren't going to shoot them, leave the gun holstered or in a safe place. If you aren't justified to shoot someone, or are but don't plan to use it, a gun in your hand is simply a liability to you. It prevents you from using that hand for other techniques, and can more easily be taken or rendered unusable by the subject.
In Canada the fact that you aren't permitted to carry a firearm for self defense means that placing such an accessory on a firearm would almost automatically prove the prosecution's case if they ever wished to charge you for carrying a weapon as your accessory is only useful in a defensive situation. If you are looking for something just to look cool, then go with the pistol bayonette. Its just as useless, but will match nicely with the red in your neck.
I am not a lawyer of course, so this isn't legal information, just common sense.
