A sheath for use with a scalpel cutting device including a sheath body configured to cover a scalpel blade at a distal end of a scalpel cutting device. The sheath advantageously includes a slot formed therein that extends from a first end at an edge of the sheath body to a second end adjacent the scalpel blade so that the slot intersects the blade and the blade is exposed only within the second end of the slot. The slot is configured such that an angle between a guiding side wall of the slot and the scalpel blade at the point of intersection is greater than 105° and less than 180°. In another embodiment, the ratio of the length of the shortest side wall to slot width is at least 2.
