I'm not sure but I think that he's pretending to be blind so he will appear weak to his enemies (either the faction that supports his younger bro, the crown prince or the faction that supports him, so they won't harm his younger bro to make him the crown prince) or the typical cliche where the king father doesn't like him and will have him killed if he appears the slightest threat to the seat of the king
20+ chapters in, and I still don't get the plot ╥﹏╥ can someone help me understand where is this headed? Like why is he pretending to be blind? What's with the two sisters? And others???