Never used a pasco. Does the metal shaft of the wrench pop or slip when you have reached preset torque of the wrench. If so I would say that it gives you the ability to apply more torque than the preset amount built into the handle.
The lever is used to reverse the wrench to loosen whatever nut/screw you were working with. Easier than grabbing another wrench when you already have the torque wrench in your hand.
I appreciate the replies and that makes total sense. I wasn't sure if it was a lever to reverse the ratchet action like a regular automotive ratchet. But I get it - a lever to manually loosen the bolts