Asian stocks stumbled to their lowest in five weeks on Monday after a batch of weak data out of China raised the spectre of a sharp slowdown in the world’s second-biggest economy. The Australian dollar, considered a liquid proxy for China plays, also took a hammering and slumped to a six-month low. Data released on Saturday showed China’s factory output grew at the weakest pace in nearly six years in August, while growth in other key sectors also cooled.