As the title of honor for kizoku (noble), ason was added after the family name and ko was added after the first name for Daijodaijin, Sadaijin, Udaijin, Naidaijin (inner minister), and for kizoku or Sangi official of the third rank or higher, ason was added after the family name and kyo was added after the first name to honor them.
ちなみに貴族の敬称としては太政大臣、左大臣、右大臣、内大臣の名の下に氏の下に朝臣、名の下に公とつけて敬称し、三位以上の貴人や参議の官にある者に対しては氏の下に朝臣、名の下に卿とつけて敬称した。