The man was a power hungry conqueror. Once he had the power he sought he no longer kept up appearances. He was an abuser of the worst sort. Brandon did a good job in a single chapter making me loath Gavilar with every fiber of my being. Seriously, he wanted Amaram to be his son in law? That would have ended well. Though it explains Jasnah's disdain for him. It also makes a lot of sense Gavilar would only trust Sadeas to a point. Take your fellow son of honor the most disciplined general in Sadeas' camp and align him legally now the man most capable of doing you immediate harm is seemingly taken out of play. He is detestable, but seemingly not a fool. His desire to have a legacy truly made him a dangerous player on Roshar if he had become a bondsmith I shudder to think what might have happened.