Police said a member of the public handed in the collection of samurai swords after they were discovered in the city on September 22.
They have now been seized and will be sent for destruction.
It was already illegal to possess a knife or offensive weapon in public, but the Offensive Weapons Act – which became law on July 14 – made it unlawful to possess certain rapid firing rifles, specific types of knives and other offensive weapons in private.
The list includes zombie knives, cyclone knives, knuckle-dusters, death star knives, flick knives, gravity knives, batons, disguised knives, push daggers and other offensive weapons.
Anyone unlawfully possessing a firearm covered by the ban will face up to 10 years in prison, and anyone who owns another weapon covered could face up to six months behind bars and a fine.
Temp Chief Insp Dave Oldfield, of Lancashire Violence Reduction Network, said: "We are fortunate that knife crime is low in Lancashire, at around one per cent. Even so, it remains a top priority and we are serious about tackling knife and violent crime together with partner agencies.
"The change in legislation is welcome and will help officers to take dangerous weapons off the streets and make it more difficult for people to obtain knives and other bladed articles in the first place.
"Turning our focus to prevention, there is a lot of multi-agency early intervention work being done across the county to support communities and young people and encourage the young into meaningful activities, education, and employment. This work is vital in steering young people away from crime."
Another legal amendment, the Antique Firearms Regulations 2021, also provided the first legal definition of an 'antique firearm' to prevent criminals gaining weapons for illegal uses.
This meant owners of firearms which were no longer classed as antiques had until September 22 to apply for a firearms certificate which would allow them to own the weapons legally, or surrender them.
Andrew Snowden, Police and Crime Commissioner for Lancashire, added: "Tackling knife crime and violent crime generally is extremely important and saves lives.
"By making these dangerous weapons harder to obtain and easier for officers to remove from our communities, we will be able to keep more people safe."
If you have any information about knife crime in Lancashire, contact the police on 101 or make a report anonymously through independent charity Crimestoppers on 0800 555 111.
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