A surgical instrument includes an end effector, a handle assembly, and a firing assembly. The end effector includes a first jaw, a second jaw, a knife, and an electrode assembly. The second jaw pivot between an open position and a closed position. The handle assembly includes a housing associated with the first jaw and an arm associated with the second jaw. The arm can pivot the second jaw between the open position and the closed position. The firing assembly can actuate the knife between a pre-fired position and a fired position. The firing assembly includes a first body slidably attached to the housing and a second body slidably attached to the arm. The second body couples with the first body when the second jaw is in the closed position. The second body decouples with the first body when the second jaw is in the open position.
