Retailers can immediately restrict the sale of knives and replica firearms after Queensland's parliament passed laws banning their sale to minors.
The state government had moved to bring forward the legislation after initially introducing a bill in November.
It follows the introduction of "Jack's Law" in 2023, created after the fatal stabbing of 17-year-old Jack Beasley on the Gold Coast in 2019.
It also expanded legislation to allow police to use personal metal detectors or "wands" to search people in so-called Safe Night Precincts as well as on public transport.
It is now an offence to sell knives, gel blasters and edged weapons like machetes, axes and swords to juveniles in Queensland.
The maximum penalty for possession of a weapon in public will increase from 12 to 18 months' imprisonment for a first offence, increasing from 18 months to two years for the second offence.
The reforms have been welcomed by Jack Beasley's father Brett, but he said more legislative changes were necessary.
"I believe that the whole Youth Justice Act needs to be rewritten. I mean, the kids back in those days aren't the same as they are today," he said when asked about juvenile crime.
Michael Stewart, who lost his teenage son Balin in a fatal stabbing, called the new laws a "baby step" but believed education remained a priority.
He runs the Balin Stewart Foundation that aims to reduce knife crime and people carrying weapons through education.
"We were blindsided so awareness is something that's dear to our heart," Mr Stewart said on Wednesday.
"My main focus is educating teens and getting teens to actually not want to carry a knife, that's the No.1 step.
"If other kids go 'hey, if you're carrying a knife, I'm going to tell police on you, it's not something that we put up with in our community', then that's the way to go."
Police have seized more than 450 knives and dangerous weapons since the introduction of Jack's Law.
Police Minister Mark Ryan said the new laws further support the impact Jack's Law is having on community safety.
The state government has committed $6 million towards knife prevention and education campaigns, including $500,000 over two years to the Beasley Foundation and $200,000 over two years to the Balin Stewart Foundation.
