1) This was originally a small knife intended for making and repairing quill pens and it was kept in a sheath.
References date from the 1400s and there is mention of your pen knife, a right Sheffield knife, in 1590. Later, ‘penknife’ was used of almost any kind of folding knife, although one used for shaping quill pens is said to have developed in the early eighteenth century. The type of penknife that we are now familiar with has a jointed blade or blades which fit inside the handle, and among those found in the mud banks of the Thames are several which are considered to date from the late 1600s. In 1733, Richard Oates of Barnsley was stabbed with a penknife into the breast
William Birks was a penknife and razor maker in Norfolk Street in Sheffield in 1766 and Gales and Martin’s directory of 1787 lists pen and pocket-knifemakers. Cutlers took the skill to other areas, as this entry in a York register shows: 1812 Joseph Fletcher of Fossgate, cutler, St Crux.