I've only ever had my hand luggage weighed once - a couple of years ago either at Bangkok or Hong Kong. I'd already checked in and was heading for the emigration counters when I nearly died .... there was a guy with a big weighing machine!!! OMG. My case was 11kg! but he asked "is there a computer in there?" and when I said there was, he said ok. Just as well... what would I have been able to do at that point seeing my cases were now on their way to the cargo area? stupid place to weigh your bags.

Remember when departing from Melbourne (and I presume you are) that they have an individual bag weight limit of 32kg. (They say
it's Occ. Health and Safety regulations... baggage handlers aren't supposed to lift more than this)
I've seen people actually have to repack their bags at checkin and put stuff into plastic carrybags.