First, having a knife is not the same as having a weapon; a knife only becomes a weapon if you intend to use it as such. This is likely a good thing about the way the law is actually worded. While the police may sometimes use terms like "legitimate purpose" with respect to knives, the law simply says you can't carry one with the intention of using it as a weapon.
Second, as dougwalkabout said, there must be a valid reason for a search to be considered legal.
Apologies, it seems the Canadians have taken hostage this thread.
As previously mentioned, the police are seeking a proactive measure against increasing urban violence by utilising existing law. As noted by dougwalkabout - does the law support the current initiative? Ultimately, time and the courts will decide.
The LEOs in Edmonton are now having to substantiate the intent of the person in possession of the knife and I don't envy them the task. Although, this would seem an obvious measure of common sense - common sense is not nearly so common.
My greatest fear is that we descend into a situation similar to what is happening in NYC - where Doug and Kniferights.org are currently having to issue a court challenge against the office of the DA to re-establish the boundaries of current law.
The public needs to be reassured that it is not the legal knife owner they need fear. Those that subscribe to this forum see them as tools for everyday use. However, that is not how the vast majority view knives and it is going to be an uphill struggle to convince them of otherwise.
And it is probably time to end my rant.
P.S.
Dennis, I'm sorry I didn't reply to your comment from a previous posting.
I found this article in the Friday edition of the Globe:
Gun Collector Sues Toronto Police Take care everyone.