A Striking Knife is a very traditional tool used by woodworkers for decades to mark-out cut lines on a board. It was probably developed in England but the origin of who by and when is lost in the mists of time.
One side of the blade is dead flat and rides snugly against whatever reference you are using as a guide (for example, a steel rule) and the other side is beveled evenly to the center from both edges of the tool. This design allows you to move the sharp knife tip smoothly in either direction without lifting it from the surface - a great aid to accurate work.
Every woodworker, whether casual or professional, should have this in his or her toolbox.