The Grandmaster... A Peasant?

Jiang's father is the swordsman known as the finest blade in the world, and he raised his son to chop wood and farm, saying that was all he would ever be good for. The boy learned the sword anyway. Nine years ago something happened between him and a girl, and his father drove him off the mountain over it. He reaches the capital and meets a young prince there. In a duel in the imperial arena he uses what he actually knows, and the palace takes notice. His wife and son are now exposed to the court's power struggles, so he claims his inheritance openly as the heir of the finest blade in the world. He beats several strong opponents. One of them, from his own clan, begins to hate him for it.