Can this really be true? Why yes my friends it can.
Anthony Bowman, 19, pleaded guilty to displaying the image on Bebo between January 2006 and July 2008.
His case came to light after police conducted a trawl of the internet in a bid to cut crime and disorder.
Bowman was then identified by officers from the Strathclyde force's Violence Reduction Taskforce.
The teenager's case was reported to prosecutors as part of Operation Access - an ongoing campaign against violence.
Kilmarnock district procurator fiscal, Les Brown, said: "This case demonstrates the benefits of using creative investigative techniques to gather evidence of crimes of violence and anti-social behaviour.
"It sends a clear message that those responsible for such crimes cannot escape justice.
"During this operation, we have worked closely with local police divisions to ensure that cases detected through internet sites can be prosecuted effectively.
"Knife crime blights many local communities and we are committed to taking prompt and effective action to pursue those responsible and stop them in their tracks."
Ch Supt Bill Fitzpatrick, of Strathclyde Police, said Operation Access had been introduced to "crack down on youth violence and anti-social behaviour within communities across Ayrshire".
He added: "It provides us with an opportunity to identify young people who associate themselves with violence and the tools of violence.
"It is one strand of a very comprehensive strategy intended to bring about a reduction in violence by tackling it at source and in the most direct fashion.
"Youngsters who use social networking sites irresponsibly should be warned that their activities are being monitored and they may get a visit from the police."
Emphasis added, of course. Makes you proud to live in this country doesn't it? Apparently the poor kid was convicted of the pretty heinous crime of waving-a-sword-about-in-a-public-place (an being photographed doing so, of course). This is the kind of country we now live in. Happy times, eh?
Question for the lawyers out there: if the police were somehow to access, say, Facebook pages that had been designated "For Friends' Viewing Only" would that constitute an illegal search? And, for that matter, even if your account is "public" what grounds do the police have for mounting this sort of fishing-expedition?