It is legal to carry any slipjoint knife (non locking blade) with a blade of 3" or less, no reason is needed but it can still fall into the offencive weapon category if you threaten someone with it.
I carry a small Case whittler with me everywhere, at all times.
ANY knife ,sword ,machete,chainsaw can be carried, if you have good reason for it.
If you have any of the above with you in the car, with no good reason ,this is an offence. unless locked in the boot
( NOT in the hatchback, ie in the back of the landy, as the inside of your car is a public place.
ATB