If you are planning on getting this to maximum here’s how I unlocked this.
Obviously keep doing nice things throughout the game to increase your honour level as much as you can but make sure you are doing Leopold strauss’s Missions. The debt collection ones. During chapter 6, you will need to go and collect debt off of two people. If I remember right one was called J john and the other was called Mr. Londonderry or something along those lines.
During these debt collections you can choose to forget the debt for the first one which will give you honor, and for the second person you can forget the debt and give money which will give you lots of honour.
Once you have done this, you will need to confront Strauss. After you get back to camp and confront him, a cutscene will play out and after this, you will be given a LOT of honour. If you still don’t have enough, you should be Very close.