In the morning of the day after their arrival in the Goblin Village, Eiro was sitting on his 'throne' and looked at the arena that had been constructed in front of him. Gobo stood on one side, and Kitsue stood on the other.
Gobo stared back at the Kitbold, who seemed to be more than just confident that she was going to win this fight and make Eiro hers, although the Demon thought he made it more than just clear he wouldn't be with her even if she managed to beat Gobo with just a single hand. Obviously, Eiro could have made such a promise to give Kitsue more motivation and stop her from complaining for now.
After all, there was literally no way for Gobo to lose against her. Only if he just sat there the whole time would she be able to beat him. But even then, even if there was no way Gobo was going to lose, Eiro knew that he had to make sure Kitsue figured out who was the Lord here. Who it was that held the power, that held the right to command.