This happens to be one of my favorite topics. So I will just jump in, head first!
THE GUN: Easiest weapon to defend against (within reason). With the gun, you simply need to be out of the “line of site” of the barrel. Granted you need various tools like: misdirection, retention, disarming, countering, striking, kicking, breaking, taking down, and a few other choice skills.
When in close or even at kicking distance, although scary and of course potentially loud, you can easily defend yourself.
The further away, the more difficult. Closer is preferred unless you are further away and you can get behind something solid or run away and stay out of line of sight.
When training, never give the gun back immediately. Do not imbed this habit of suffer the fate of others that did the same thing.
THE CLUB: Typically a stick anywhere from about 12 to 30 inches. What sets this apart from the bat is that it is a 1 handed attack. So because of that there is less body commitment.
Being that most people are right handed, we will simply assume all are right attacking people, just to keep things simple.
So usual attacks are side, overhead, poking, and the backswing. That is the order of common attacks.
Dealing with the side, overhead, and backswing is simple. The closer you are, the safer you are. If you start too close, well then your attacker is going to take a crack at you. I recommend keeping a distance that is just out of their range of attack. This forces them to commit moving or stepping forward to attack. It is at this time you move forward. This allows you to not only crowd control them but if you miss the block/deflection, only their arm may hit you and not the stick. Just like baseball … if the ball hits you, it drops, if it hits 3 inches up from your grip, the ball travels a little, if it hits halfway up the bat, then you are getting some distance, if you hit near the end of the bat, you got yourself a homerun !!
Same rules apply here as any other weapon. Once you have blocked/redirected/etc then you retain/disarm and strike/kick/break them. A complete disarm is always preferred.
THE BAT: Similar to the stick but they are dealing with a weapon where 2 hands are needed to control the power and the overweight of the bat. Also, because both hands are trying to maintain control, the whole body will be committed. Same types of attacks as the club. Again, closer is safer!
For both club and bat, if you have the option to keep a good distance, then run, place objects between you and them. The techniques are for when defending yourself is the last alternative. NEVER STEP BACK TO BLOCK !
THE KNIFE: The most deadly in my opinion. It does not break easy, it does not run out of bullets, it can be thrown, it can be used a crazy amount of times before it needs to be sharpened, it is easy to sharpen with the right tool or a simple piece of pottery. It can be hidden. Make no mistake, this is nasty and deadly.
There is an argument that occurs between martial arts instructors and police officers about this and they are both right. You only need perspective to start.
The Martial Artist usually tells you to keep your distance, similar to the club, just out range. Then when they attack, you move to create a safe buffer (not usually closer as you need to be much more refined and skilled), lean enough that if you miss your block that you still don’t get cut or stabbed, then block/deflect/etc and either disarm or get immediate retention. Then next is devastating your opponent immediately. There is more but you get the point.
The Police Officer will respond by more often getting in close and controlling the attacking arm, breaking the arm, controlling the arm, taking them down, etc. then finishing them with a control, if the circumstances allow.
Usually they have drawn their gun, so above is an example of the officer caught off guard.
Both sides are right. Most times when the average person is being attacked, it is more a mugging and the bad guy wants something. If an officer is being attacked, I assure you, there is no intention to take his lunch money. An officer being attacked is having deadly force being used against him and he (if properly trained) will act in kind.
I know a few people will argue some aspects above. That is fine, but common sense and a simple understanding of the history of attacks is all you need to see what I am saying to be true.