Yesterday I wondered to myself if "Ar" might be a French word or Title, such as Mr., etc.
So, I went to an online French / English dictionary.
The word "Ar" refers to "prince / princess" ... "your highness / his highness / her / highness."
William Barron said that Francis was a Huguenot. So, I went to a site about the Huguenot's and here is some of what they said: (Note the French nobility).
"The Protestant Reformation began by Martin Luther in Germany about 1517, spread rapidly in France, especially among those having grievances against the established order of government. As Protestantism grew and developed in France it generally abandoned the Lutheran form, and took the shape of Calvinism. The new "Reformed religion" practiced by many members of the French nobility and social middle-class, based on a belief in salvation through individual faith without the need for the intercession of a church hierarchy ..."