by X-ray:
I put it to you that most, if not all of those weapons were handed in by individuals who had no intention to use them in a crime.
No intention to use them in a crime? With knives, the crime is using them in an argument. Nobody robs a bank with a knife, you can't snipe people down with a knife and normal police on the street are fairly well protected against knife attack.
The crime would only occur if the individual felt threatened enough to pull the knife, it would rarely be used for indiscriminate killing (although the threat to use one in a mugging might be an exception).
Knives are a defensive tool and can be resorted to with ease as opposed to the more difficult diplomatic route in a confrontation.
The general purging of knives out of circulation can be productive.
Master criminals may be able to get hold of knives with ease but taking them out of circulation certainly makes it harder for the teenage gang members.
Although, depending on the roughness of the area a broken bottle, screwdriver etc. can be equally as offensive in close quarters.
Nobody butters their toast with a Rambo knife and it's very design and ergonomics such killing. They're more effective at quick and multiple kills and most importantly they're expensive. By taking these off the street you're destabilising the criminal economy - they have to spend more of their own money to 'tool up' to this specification.
