United Cutlery makes a very nice "M48" hammer that I used to carry with me specifically for breaking glass or wood doors down. Management ONCE asked if it was necessary, and I just responded that I could bring the tomahawk (same line) instead. Never a question after that, but I was put on the Saftey committee responsible for fire drills, alarms, exit notices and such.
Which then gave me the excuse to bring in 10 stories worth of climbing rope (7th floor) and 10 rappelling harnesses, with enough 550 cord to attach to them and haul back up. Management was grateful I never got to use it.