I need to know whether it is legal to carry a lockback style pocket knife with a blade of 4.5 cm in Western Australia. I know that in the US it is legal to carry a knife with a blade of less than 3 inches without 'good reason' required. This knife has a 1.77 inch blade. So, is it legal to carry it- just in your pocket? And is there any restrictions? Eg age, location, etc (obviously not trying to take it into an airport or give it to a 2 year old, but you know what I mean)

Thanks in advance :)