The welt knife is a shoemaker's hand tool that evenly cuts the overhanging leather on the sole. It has an S-shaped curved top with a cut and a small protrusion of a few millimeters at the head end, fixed in a wooden handle. The blade can also have a bent edge on one long side.
In some models the working part is protected with a wooden sheath.
See also the welt cutter. [MOT]