It's a simple solution the Chinese option, detention centres, if you are caught carrying something like that, even if you have not commited a crime, straight to a detention centre.
Get them built.
Then any family you have, will have to come feed you, as it will not be supplied by the state. Any change of clothes, to be collected and washed by the family. This way you make the family responsible too.
If you don't have family, but have savings, you will have to pay to be fed and changed.
I guarantee you, kids will soon stop carrying knives. Not all, but a large proportion of them, will no longer see it as a weapon to carry. We don't even have to put them through the courts, get caught with a knife, get banged up, end of.
We pussy foot around too much. Human rights will be crying but fook them.