The last time I flew in AU was to Canberra for one of my brothers funeral. A quick trip down and back on the same day not a big deal and because I was only there for the day I wore what I was wearing to the Funeral and only took a Carry On.
The Security took fits because I had a Tie Pin on and wanted to remove it. Didn't matter that I had a Medical Certificate for Needles and Syringes they where Perfectly OK but a Tie Pin with a sharp point on it all of 5 mm long was dangerous and not allowed.
Apparently I could stick the pin between my fingers and somehow injure someone so I just asked what about the Needles? Surely I could do far worse with those?
Their reply was No you couldn't they are Medical and you need them which is true so I just suggested that maybe if I was so inclined I would forge a Medical Certificate and not draw any attention to myself with the Tie Pin to begin with.
I returned to the car and removed the tie pin and didn't have any more issues other than a Government Representative at my brothers funeral asking why I was incorrectly dressed with no Tie Pin.

Col