So according to kingdom.wikia
"Hou Ken's abilities are limited to being perhaps the strongest single warrior in the story thus far. His character is shrouded in some mystery as to his capabilities as an army commander. He has however still been a great asset to the armies of Zhao as a symbol for morale and by his mere presence causing enemies to have fear and the armies of Zhao to fight harder. In combination to his own independent actions, many opportunities were created that allowed Zhao to overwhelm the opposing armies."
So how strong is Ken, and will Shin be the one fight him?