A surgical instrument end effector assembly includes a first jaw member defining an insulative tissue-contacting surface and first and second electrically-conductive tissue-contacting surfaces disposed on either side of the insulative tissue-contacting surface. A second jaw member includes an ultrasonic blade body positioned to oppose the insulative tissue-contacting surface of the first jaw member. The first jaw member is movable relative to the second jaw member between a spaced-apart position and an approximated position to apply a first grasping force to tissue disposed therebetween. A slider is movable, independent of the first jaw member, between a retracted position, wherein the slider is disposed proximally of the first and second jaw members, and an extended position, wherein the slider extends about the first jaw member and urges the first jaw member from the approximated position further towards the second jaw member to apply a second, greater grasping force to tissue.