John in NYC today, the "gravity knife" charge is a A Misd ( a crime one step below a felony) and permission needs to be granted and additional forms filled out and signed off on the allow a DAT ( Desk Apperance Ticket) to be issued in lieu of putting someone through the system, so unless you truly have a very good relationship with someone, almost no officer will take the extra effort needed to not keep you in jail over night. A summons (really a Criminal Court Summons) is normally only issued for the NYC Amin Code offense as that is only a violation and not a crime by NYS PL definition. That is the way it is now in NYC, so I am not sure if you are quoting old methods.....
Thank you for the clarification, you are correct (I checked). And yes, unless you have connections (or really good luck), don't expect any favors.