Here's a great little defensive item that Fred found and has put to good use.

It is an every day writing utensil that you can carry with you anyplace. In reverse grip, the chromed metal body becomes a blunt strike device straight out of your shirt pocket. Remove the cap, and due to the acute angle of the cap, you have a DNA sampler. Of course, you can always use it to jot down a note as well. ;)

Uses standard ink cartridge.
Weighs 25 grams.