The Pueblo was hardly a warship.
Well...she was a ship of the U.S. Navy, and did have two .50 cal machine guns, so that does technically make her a warship.
COMNAVFORJAPAN (ADM Johnson) was against arming the vessel, and suggested the weapons be stored below, but made it clear that it was up to the Captain. In the end, they did have the guns on deck covered with tarpaulins, and never uncovered them.