An ultrasonic surgical instrument comprising an elongated body, a clamping assembly and an actuation mechanism configured to actuate the clamping assembly, comprising: a handle portion including a handle body and a stationary handle; a movable first trigger assembly having a first trigger and a first mechanical advantage mechanism; a movable second trigger assembly having a second trigger and a second mechanical advantage mechanism; wherein the first trigger and the second trigger are arranged on opposing sides of the stationary handle of the handle portion and wherein said first trigger and said second trigger are configured to be contacted by an operator grasping the stationary handle by four fingers except for thumb of a hand and a portion between thumb and index finger, respectively; and a driving member in engagement with the first trigger assembly and the second trigger assembly, respectively; and wherein the first trigger assembly is engaged with the second trigger assembly, and the first trigger is movable independently with respect to the second trigger during a portion of movement of the first trigger and/or a portion of movement of the second trigger; and the first trigger assembly and the second trigger assembly are applied different mechanical advantages, wherein when force is applied onto the first trigger and to the second trigger said force is being delivered to the driving member through the first and second triggers (4, 5) and the first and second mechanical advantage mechanisms, respectively; further comprising a biasing member configured for stopping the second trigger assembly until the force against the driving member exceeds a predetermined limit. a handle portion including a handle body and a stationary handle; a movable first trigger assembly having a first trigger and a first mechanical advantage mechanism; a movable second trigger assembly having a second trigger and a second mechanical advantage mechanism; wherein the first trigger and the second trigger are arranged on opposing sides of the stationary handle of the handle portion and wherein said first trigger and said second trigger are configured to be contacted by an operator grasping the stationary handle by four fingers except for thumb of a hand and a portion between thumb and index finger, respectively; and a driving member in engagement with the first trigger assembly and the second trigger assembly, respectively; and wherein the first trigger assembly is engaged with the second trigger assembly, and the first trigger is movable independently with respect to the second trigger during a portion of movement of the first trigger and/or a portion of movement of the second trigger; and the first trigger assembly and the second trigger assembly are applied different mechanical advantages, wherein when force is applied onto the first trigger and to the second trigger said force is being delivered to the driving member through the first and second triggers (4, 5) and the first and second mechanical advantage mechanisms, respectively; further comprising a biasing member configured for stopping the second trigger assembly until the force against the driving member exceeds a predetermined limit.