Bernina torn blade

The original Bernina twister knife is for twisting seams loose or opening homemade buttonholes.

Between the teeth of the fork portion is a sharp edge that acts as a knife. One of the teeth is longer than the other. This one is meant to slide under the stitching, causing it to naturally slide over the blade and cut through. The other prong of the fork is shorter and has a blunt tip. This prevents damage to the fabric.