No, really, look what it has done to your poor legs!
It increases damage and swing speed. Note that the higher you raise it, the more points you have to sink into it to raise it further. I think the best amount of WPF is reached with WM5, which leads to 145 WPF on level 30. With WM6, you only get to 154, which is not worth it IMO. Better skill throwing or riding or make a 2h/1h hybrid for great maul lolz or pole/1h for long maul lolz.