No person shall be allowed to possess, use, or threaten the use of any weapon, including toy or replica weapons, or other object in such a manner that it may be considered a weapon in library buildings or on library property, with the exception of weapons carried by authorized law enforcement agents. One-time exceptions to this policy may be made by the library director, in writing, for objects used in conjunction with a library program or used by a meeting room user group during the course of their meeting.