I have consulted with a lawyer, various lecturers at my university (a security and pre police force and intelligence training institute) and been over both my state laws, regulations and the federal customs act. Batons are regulated, the comtech stinger is prohibited both at an import and state carry level, and due to recent events in my city, police are zero tolerance on knives. Due to a section of the weapons legislation in my state, anything carried with the intent of it being used as a weapon is a dangerous article. If the police, for any reason, suspect you of carrying a weapon, they can search you. You MUST have a VERY GOOD reason for carrying a knife of any description or your in for a bit of jail time. The courts in my town do not mess around with knives.
One of the few viable self defence weapons I've been able to locate that doesn't fall under the definition of a prohibited weapon is a lead filled soft sap. Because I can use it as a massage tool, I could carry it without fear of a charge.
So, aside from the obvious 'aim for the head and hope to cause unconsciousness' or targetting the sciatic nerve, what fighting techniques could I employ?