Here is a self-defense pen that comes with a built-in clip that doubles as a handcuff key. The UZI Tactical Pen has a lightweight, aircraft-grade aluminum construction. It has a striking point and glass breaker tip. The pocket clip swivels around to be a handcuff key.
The UZI tactical defender pen weighs only 1.59oz, measuring 6″ long. Not too expensive either.
[where to find it]