The possession or carrying of a hand gun is limited to an on duty firearms trained police officer, or an on duty serving member of Her Majesty's Armed Forces,
You will almost certainly get a jail sentence or a heavy fine for possession of an unsheilded blade in a public place, this includes so called "Flick knives" unless you can demonstrate good reason, this does not apply to clasp knives, Swiss army knives or multi-tools.
BUT THE LAW IS MORE CONCERNED WITH "INTENT", ANY OBJECT CAN BE CONSIDERED A WEAPON "IF ITS USE AS SUCH CAN BE PROVED"
That carries a maximum penalty of LIFE Imprisonment.
We still get our share of violent crime but mass killings in public places by individuals and non terrorist organisations using Guns and Blades have pretty much disappeared.
The ownership of a Shotgun is lawful within certain limitations although ownership of a "Pump Action Shotgun" is prohibited.
I hope that helps you understand the difference between the UK and the USA in our legal attitude to weapons.
Perhaps I should add that most citizens do not consider these restrictions as a limitation on their rights but rather the actions of a community caring for the common good?

shaun