An improved surgical instrument having an end effector mounted on the end of an elongate shaft extending from a handle. The end-effector is capable of several different operations, including grasping, cutting, and sealing and/or coagulating tissue, and one of the operations is controlled by a trigger mechanism contained within the handle. The end effector includes a pair of curved jaw members and a blade assembly having a cutting blade at its distal end. The trigger mechanism is arranged to drive the blade assembly longitudinally within the elongate shaft such that the cutting blade protrudes between jaw members. In order to help trigger mechanism push the blade assembly around the curved jaws, the distal end of the blade has a graduated flexibility such that it can more easily bend to the shape of the jaw members. The distal end of blade may also be provided with a low friction coating.
