Abstract: A dispenser for serving and severing web from a roll includes a container for supporting the roll and a slotted cutting shelf over which web from the roll is draped. A swing-down cover hinged to the container carries a knife blade aligned with the shelf slot and a retractable sheath which envelops the blade until the dispenser is operated to sever the web. The sheath is an elongated flexible resilient member which is downwardly bowed so that, when the cover is swung toward its closed position, the sheath engages the web on the shelf at the midportion of the web first and then gradually engages web portions outboard from that midportion in a progressive fashion by a rolling clamping action until the entire length of the sheath is flexed flat against the web on the shelf thereby laterally tensioning the web as the blade edge projects through the web into the shelf slot.