Rank these weapons, if you were to encounter them during an attack, in order of danger in terms of fear, potential for harm and difficulty in defending against.
Gun
Knife
Blood filled syringe
Water pistol
Crow bar
Broken glass bottle
Chain
Container of petrol
Give reasons.
(* Not a Lawyer take my comments for comments in the wind *)
Hmm, In my state (Michigan) a firearm is considered a defensive weapon and all the rest are considered an offensive weapon. As in if you carry a firearm it is for defense and if you carry any of the others for use other than intended and you have a legitimate reason to use the item as intended then you are ok. Yet if you do not use them as intended then you have committed an offensive assault even if you are defending yourself. So it is an up hill battle from the legal perspective. Or it was a while back when I had done recent research. As laws change and court rulings change the interpretations of those laws one needs an expert who works in the field, and I mean a Lawyer not an officer to give them advice.
I like the answer that they are all number one as I do not know that the person is joking I have to assume they are intent on ending my life some how. Even the water pistol with Acid can blind me. Or have some drug that knocks me out and then they kill me.
Gun
Having had a few guns pointed at me, each situation is different and defense is important. From hiding, to using his friend as a body shield to raising your hands and talking to the person, as well as not being able to react at all because as you see the muzzle flash in the vehicle driving by you hear the bang in front and behind you at the same time.
Now as to defending. I do not recommend this at all. Yet if you are in grappling range (Which the person with the gun should not be) one can grab and try to keep the barrel pointed away from you. Try this with a water gun in your hand. The reaction time is slower and you can change your wet t-shirt to a dry one and try again. Yet there is a possibility as just touching it will not hurt you. Slide bite my occur.
Knife
Knives are great tools and can be used as self defense tools as well. It is easy to wiggle the blade around in a grappling situation and cut your opponent or target. Once again the one you do not see it the hardest to defend against. In a crowd of people a person walks by you and you get hit in the leg or lower back and you turn to see them and then you feel something weird and you check the spot and it is wet and you realize it is blood. Note I was lucky and it was just a leg shot for me. Other times you get lucky and see it coming and can react. Yet it is easy for them to wiggle and or change directions and you can get cut. Like my forearm just above the elbow.
Blood filled syringe
No person experience here, other than people saying they were HIV positive or Hep C positive when things started to go bad for them. This is similar to the knife as it is hard to see and easy to move. Also hard to stop if the person cares not about what you do to them on their way in. I did not mention that for the knife which is also true.
Water pistol
While a toy, it could have an acid or base that could blind a person. It could have drug that knocks you out and makes you see things and easy prey to be taken out. See gun.
Crow bar
Blunt force weapons or weapons of opportunity. These make good weapons when faced with others wth weapons or multiple numbers and you are in fear for your life. See FMA trainning on how to handle this. Lots of discussions in those threads on this.
Broken glass bottle
Glass bottles are also good improvised weapons and most start out solid and turn into broken ones once used as an impact weapon. So now they can cut people. I am not sure how many people have broken a beer bottle recently they seem to brake into lots of small pieces not like the old days of the bottles from the 60's and 70's and my guess before as well. Those could get you a nice jagged edge to work with. See knife for defense. Personally I think this would be more rare than the others for once used as an impact tool they are very small pieces
Chain
Chains are great tools. They also can be used as weapons. They provide range and flexibility. To use one well you need to practice and train with it. Otherwise it becomes a flail like device where it is bundled up in their hands and they are swinging it only a foot to maybe two beet at max. Any more than two feet and they hurt themselves by hitting themselves. See FMA for this. If they are longer and using it to wrap you up then they are trained and at that point the flexibility will make it difficult for one to see where it comes from.
Container of petrol
Gas or petrol can be light and splashed on you. It can be used as a localized grenade effect to spread the fire. This is a ranged weapon with splash capabilities. Once thrown or dumped it has been used. If done in partial then one still has a limited supply. If they are intent on lighting themselves on fire then they will also splash you. So distance is your friend. If they only want you then being close the make it hard for them to get you without getting themselves as well as possible getting them to drop it.