Actually, Abel didn't want Grand Duke Edwina to kill Prince Adolf because of him. He knew it was unrealistic to kill a person with such high status, but at least he wanted him to know where the threat was coming from.
Maybe in the eyes of Grand Duke Edwina, he was just Loraine's boyfriend, who was also an alchemist with some special ability. Only a bit of respect and benefits was enough to get him to work for the Grand Ducal Palace.
"Tell Grand Duke Edwina I appreciate it. Also, tell Lady Carrie to quickly complete our exchange!" Abel didn't say much about the 28 heads Steward Derek had brought. His voice sounded very monotone like he and Derek were just business partners, rather than close friends.