失手

a slip / miscalculation / unwise move / accidentally / by mistake / to lose control / to be defeated

to lose / to miss / to fail

hand / (formal) to hold / person engaged in certain types of work / person skilled in certain types of work / personal(ly) / convenient / classifier for skill / CL:雙|双[shuang1],隻|只[zhi1]

lit. just as humans make mistakes, so can a horse stumble (idiom) / fig. everyone makes mistakes / even the best fall down sometimes