Have you read the Post-Chaplinsky section of the article you cite? (Unless you meant to focus on the Canadian/Australian legal meanings). The US Supreme Court has been progressively narrowing what "fighting words" means over the years.

By the way, the "fighting words" decision(like the other oft-favored "fire in a crowded theater" quote) are great ironic examples of what kinds of speech you are looking to suppress - a Jehova's Witness swearing at police, and a protestor against the draft in WWI. You don't need to be imaginative to see how these "reasonable limits to free speech" will be used negatively, you only need to look at what they were created for.