The blitz was launched by Sir Ian in response to a wave of killings, particularly among teenagers, in the capital. He unveiled the figures alongside London Mayor Boris Johnson at City Hall.
They came as four teenagers remain in custody after being arrested by detectives investigating the murder of 16-year-old Ben Kinsella.
Hundreds of people, including friends and relatives of the young student, took to the streets to demand an end to knife crime.
The new figures revealed that 1,214 people were arrested for possession of weapons and other knife-related crimes between May 19 and June 29.
Many were recovered during stop and search operations in high streets and at transport hubs, while others were found in weapons stashes.
Sir Ian said the stabbing of Ben in Islington at the weekend showed "the problem of knife crime is still with us".
He said: "I know the communities of London understand that this is something they and the police have to solve together.
"I promise that the Met is in this for the long haul and we will do everything in its power to stop these murders continuing."
Mr Johnson said Operation Blunt is only one area in which the authorities are working to make London safer.
He said: "Everybody is shocked by the level of violence we are seeing, particularly towards young people in London, and we must all work as hard as we can together to reverse this dreadful trend."
Earlier, Home secretary Jacqui Smith vowed to tackle knife crime.
She said: "This is only something that we can solve if we come together - Government, police, young people, community groups - in the same way that we've done tackling guns and gangs."
Meanwhile, a woman has died after being stabbed in south east London.
The victim, believed to be in her 20s, received a wound to her upper body during the attack at around 11pm near Peckham High Street.
More than half (55%) of young people fear becoming victims of knife crime in the summer months, a survey has shown.
The poll, commissioned by BBC London, surveyed 501 people aged 13 to 18 in the London boroughs of Brent, Croydon, Hackney, Lambeth, and Southwark.
The survey also revealed 75% do not think London's mayor Boris Johnson and the government will be able to reduce knife crime over the coming months.
A spokesman for the mayor said tackling knife crime was a long-term goal.
"The solutions to these types of problems are much more long-term," said Kit Malthouse, Deputy Mayor for Policing.
"It's about intervening in schools and a cultural change to stop people carrying knives."
He added: "The survey also says that the major reason for young people carrying knives is to get 'respect' and one of the things we have to do as a society is show them how unglamorous it is actually to carry a knife."
75% disagree London Mayor Boris Johnson and the government will be able to reduce knife crime in London over the coming months
84% say it has become easier to buy a knife
26% think they will more likely be the victim of gun or knife crime than gain a good qualification
41% feel those carrying weapons should get longer sentences
6% say they have been pressured into joining a gang
63% say they feel the police are unable to protect themMost computers will open PDF documents automatically, but you may need to download Adobe Acrobat Reader.
About 45% of respondents said they knew someone who had been a victim of knife crime.
That is up from 33% last year, when the poll was last conducted in the same boroughs and among the same age group.
Fear of being a victim of crime has increased to 32% from 26% last year as a reason for people carrying weapons.
The percentage of those young people who carry knives because they "want respect" has declined from 44% to 39%, but it remains the most popular perceived reason for doing so.
The proportion who say the same of gun crime has gone up from 17% to 22% since last November.
The proportion of those who say they have been pressured into joining a gang has doubled from a small base of 3% to 6%
The survey was conducted by polling company ComRes between 21 and 23 July.
The information was weighted to be demographically representative of each borough surveyed.
In London alone, 21 teenagers have died in violent circumstances in London this year.
The most recent was 18-year-old Frederick Moody Boateng who was stabbed to death on 17 July in Lambeth.
An extra £3m to help keep young people safe in knife crime hotspots has been announced by ministers.
Initiatives include a visible police presence on school routes and dedicated officers to work with young people likely to become offenders or victims.
The money will go to the 10 police force areas in the government's Tackling Knives Action Programme.
Home Secretary Jacqui Smith said she hoped it would send the message that a knife is not needed for protection.
The announcement came hours after a 16-year-old boy was stabbed to death outside a youth club in Liverpool.
The teenager was with two friends when he was attacked by a group of youths outside Shrewsbury House Youth Club in Everton at 2040 BST on Monday.
| Young people tell us that the
period after school can be when conflicts
arise and an increase in police presence can help them be and feel safe
Met Deputy Assistant Commissioner Alf Hitchcock
Ms Smith told the BBC that tougher laws and enforcement were already having an effect.
She said: "This is obviously a tragedy for the family up in Liverpool, and the reason why we need to keep building on the work that we have undertaken to tackle knife crime.
"All of these things are making a difference. Any young person killed in a tragedy like last night is one too many.
"But we've got to carry on with the efforts that we've put in place and to work alongside the community and the police to do that."
Some £2m more was announced earlier this year for the 10 areas, which are London, Essex, Lancashire, West Yorkshire, Merseyside, the West Midlands, Greater Manchester, Nottinghamshire, South Wales and Thames Valley.
Metropolitan Police Deputy Assistant Commissioner Alf Hitchcock, head of the Tackling Knives Action Programme, said the police presence on school routes would target the time of day when trouble could occur between youths.
"Young people tell us that the period after school can
be when conflicts arise between different groups and an increase in
police presence and in other visible signs of authority can help them
be and feel safe and secure," he said.
"This additional funding will assist the 10 Tackling Knives Action Programme forces in further building on the tough approach towards those who carry knives which Acpo [the Association of Chief Police Officers] is leading across the police service."
Shadow home affairs minister James Brokenshire said the initiative was too limited in its scope.
He said: "I support any mechanism that will cut the appalling crimes that we've seen on our streets.
"My concern about this approach is that it's just too targeted. It's saying that the problem is just in certain areas and at certain times of the day, in other words after school.
"Tragically, with the incident we saw last night, it didn't happen just after school and it didn't happen just within the vicinity of the school."