The "right" to bear arms does not exist in Australia. We have very strict gun laws and very little gun crime as a result - the last time there was a mass shooting was in Port Arthur in 1996. And I can't imagine how there could have been a better result from the siege even if the hostages had weapons of their own.
When I first trained as a bank teller in the late 70s we all had guns in holsters in our teller's boxes, and had to attend mandatory weapons training. However by 1980 they'd all been removed, as they found that staff were ten times more likely to be injured or killed during a holdup if they tried to use their weapon - nothing makes a bandit more nervous than having a gun waved in his face.
We do get the odd drive-by shooting; the criminal element will always be able to lay their hands on a weapon but at least it's harder for the average person to pick up a gun and go postal.
But there's really no protection from the lone nutjob on a crusade. It's frightened me, and made me angry that it could happen here, and I'm beginning to get an idea of how US citizens must have felt after the violation of 9/11.