A supremely imaginative blending of A History of Violence, TV’s Sherlock and Chang Cheh’s 1967 classic One-Armed Swordsman, Wu Xia is a visually ravishing, compelling and (rare in the genre) thoughtful kung fu actioner, with Hong Kong superstar Donnie Yen taking on both acting and choreographic responsibilities. In 1917 southwestern China, an investigation into the killing of two robbers by a seemingly mild-mannered paper-maker, leads forensic detective Xu (Takeshi Kaneshiro) inexorably towards the infamous 72 Demons gang…