The penknife originally served to cut the tip of a quill pen and to scrape away ink stains from parchment or paper, like an eraser knife. It has a narrow, sharp blade measuring between 2.5 cm and 4.5 cm in length. The penknife is now usually a cutting knife, exceptionally with a replaceable blade, which is used for all kinds of purposes, including as a nail knife. A light (approx. 10 g) model, from the Christy Company, contains a blade that can be slid into the handle in four positions to determine the length of the blade.
In addition to the large blade, many pocket knives also have a small sharp blade that is used as a pen knife.
Not to be confused with the scalpel. [MOT]