The shoulder knife is a manual tool used by the marquetry worker to cut veneer (1). It has a blade (approx. 6 cm) with a straight or curved edge. The end of the long wooden handle (approx. 57 cm) is slightly curved and rests on the shoulder of the user. This way he has more control over the knife and can put more pressure.
It is also sometimes used as a chip carving knife (2).
See also the cutting gauge. [MOT]
(1) In the 18th century, the cutting gauge was preferred over the shoulder knife. See ROUBO: 847.
(2) From DICK catalog: 53.