Actually, there was one thing Wizard Dunn did not tell Abel. The first thing that required the spirit to change its decision was the Wizard Union's credit points. If you gave enough credit points, the spirit would do what you asked.
After Abel left Wizard Dunn, he returned to Harry Castle. First, they handed over the large amounts of ready-made rabbit essence to Bartoli and explained how the domain would operate from now on.
Abel handed over Earl Domain's military to the Knight of Bennett--especially the elite knight brigade. With Abel's knight training potions and those magical wheat bread as a reward, it had made the Knight of Bennett's job a lot easier.
By that point, everyone knew that the Knight of Bennett could become a Sir if he got another merit. As the real father of the City Ruler, no one would stop the knight of Bennett from increasing his status.