Malaica was very well informed, and she knew exactly about the woman who was standing beside Aragon. And the name Daewynn refers to the imperial house currently ruling over the empire.
Right before Renqinor had gone to battle, the reigning emperor had announced Renqinor would become the next emperor, succeeding him. But he didn't return from the battle. Then the throne was passed onto Renqinor's brother.
The rightful heir to the throne was Renqinor, but he was killed. And now that Aragon had come out and revealed his name, he had the right to claim the throne and succeed his grandfather.