The Sages are the intellectual masters for a Noble House. Like Knights and Baronets they are considered to be Middle Class and are chosen due to great mental feats that they have accomplished. Sages are not considered to be a noble but they are considered more than a 'typical' commoner. A Sage chosen for a noble house is someone who has more than proven that they have mental skills that are hard to rival. The Sages are always a commoner and they serve as the people who handle mental warfare for a noble house. They can often be called on to help assist with plans of attack or to solving a problem that is not easy to figure out.
Sages are not abundant as a noble house can only have one, like Knights and Baronets. Removing a Sage is no easy tasks, as they are selected because they are the 'best of the best'. It has to be something pretty big for a Sage to lose their position. Sages are only removed should they disgrace the noble family they serve. This is a hard feat for a Sage to do considering they are focused on intellect. They would have to take actions that will cause a house to look the fool or unwise. Should a Sage manage to do this they are removed from their position. They aren't banished or anything but they do have to live with the shame they are not considered an intellect that is one of the best of the best anymore.
A Sage losing their title is unlikely to regain it for any noble house but there has been occasions where a former Sage has risen from disgrace to be considered one of the top tier intellects once more. Though, to rise to the level after being disgraced borders on being impossible. A Sage is also unlikely to be picked up by a noble house should they fall from grace. VERY extreme cases have the Sage put to death for their failed actions but the actions they take have to be a grave danger to the noble family they serve.