Okay, I’ll ask the 18-year old Ozzie from Sydney currently living with us for clarification...
Regarding knives, he said you couldn’t walk down the street with one. Maybe it’s okay to possess one in one’s house?
You can’t carry a knife for self defence. You can carry one if you have another reason to carry it.
As very few teenage boys are fishermen, leather workers, or similar, police will tend to assume they don’t have a good reason to be carrying a knife unless they can explain it.
I carry a pocket knife everywhere, and if I am asked why - as I have been once when he pinged a metal detector, I simply say it’s a useful tool that I got used to carrying in the navy and there’s no problem. A teenage boy might not get as easy treatment as I do.
Teachers, by the way (I am one) will often tell kids it’s not legal to carry a knife, because so many kids are using them in fights and stabbing each other. It’s not strictly true, but the law is complex and trying to get it through to kids isn’t easy.
I’ve just looked up the precise wording.
It is unlawful to carry a knife without reasonable excuse.
What this means is that if you are carrying a knife, you can be asked why, and if your explanation doesn’t match the knife, there could be problems.
A fishing knife - and you’re going fishing - your fine. A fishing knife, and you’ve never fished in your life - problem.
Basic pocket knives are considered tools, and most people have a valid reason to be carrying a tool. But if police find them on a group of kids who are the type they think are likely to get involved in a fight, they are fairly likely to treat it as a weapon.
A lot of Australian law relies on commonsense.