tia, gravity or both; vi. ???disguised knife???, any knife designed so that it is not readily recognizable as a knife, and appears instead to be some non-threatening item such as a lipstick, pen, belt buckle, air gauge, or any other common item; vii. ???undetectable knife???, any knife or other instrument with or without a handguard that is capable of ready use as a stabbing weapon that is not det