The law

Carrying a knife that can be used as a weapon in a public place is against the law.
Any object that could be used to inflict damage to another person, or to threaten someone is an offensive weapon.
If you are caught carrying anything that could be used as a weapon in a public place you will have to explain to a police officer why you are carrying it. If you cannot give a good reason you can be arrested on the spot. Carrying a weapon for your own protection is not an excuse.
It is illegal to carry a knife for self-defence
If you use a knife in self-defence you could end up in prison.
It is an offence to bring any weapon into school, you could get up to four years in prison.
It is illegal for anyone under 18 to buy a knife.
If you get someone else to carry a knife for you, you could get up to four years in prison.
Police can and will search someone if they believe they are carrying a knife. Police and school staff can also search young people for weapons at school.

It is illegal to carry a gun, or anything that looks like a gun in a public place.
It is illegal to use a gun, or anything that looks like a gun to intimidate or threaten someone.
It is illegal to get someone to hide or carry a dangerous weapon for you. The maximum penalty is ten years in prison.
It is illegal to sell an air weapon to any person under the age of 18.
It is illegal to fire an air weapon anywhere other than on private land.