Guan Yu's Blue/Green Dragon weapon in DW7

How is this obtained? I have been told that it is by completing the Pike Conquest Mode area, you know where you obtain the legendary weapon in the pike square and you fight Guan Yu at the end? Well yeah I tried that, and that did not get me his legendary weapon. It got me some crappy Golden Glory pike, and that is not what I want. Does anyone know how this is obtained?