Pen

A magical pen, that once uncapped, can be turned into a sword, used for fighting monsters. A "Pen" is used by Demigods, such as Percy Jackson.

Leo Valdez: Hey, Percy what is your weapon made of?
Percy Jackson : A Pen!
Leo Valdez: Wait, What?
Percy Jackson : * Uncaps Pen*
Leo Valdez: Holy Hades ! That is cool!
Percy Jackson : Thanks, My Dad gave it.