Have that extra measure of self defense in hand with a CobraTec OTF Pen Knive.  This fully functional ink pen contains a concealed knife blade. Just twist the handle to reveal the pen point or push up on the clip to extend the 1.75 inch stainless steel blade that is housed in a durable, aluminum pen casing.
 
1.75 inch concealed stainless steel blade
Durable aluminum pen casing
5.625 inch total length
Contains a replaceable black ink cartridge