Maybe the duke shouldn't have hired a teacher whose only brother was killed in the war against Grezekaia. What was he thinking? It's impossible he couldn't have found another one. There would be plenty of second, third, fourth sons of minor gentry who aren't inheriting their father's title and thus must find some other way to feed themselves. It doesn't even need to be someone from a noble family. It could be a son from a high ranking civil servant's family. The duke is a straightforward man, not an petty elitist, so I doubt he would mind, as long as the teacher is competent. The duchess must certainly wouldn't mind, considering her background. They could have also hired a woman. Since Clarisse is receiving education, doesn't it mean well-off women in general receive education?