It's a stretch to land and doesn't really do damage unless you have a considerable speed bonus. With the turn speed bonus nerfed, this attack seems more like a gimmick attack more than a threat in the 1her's arsenal. The overhand attacks tend to not land when they should as well, making the 1h a left swing/right swing weapon as a whole. I don't know what could be done to help the 1h stab, but it feels like a new animation (which has been hinted at being in the works), or a straight up damage or speed stat buff would help.