Because she was supposed to be a muscle brain in the first place, in the future chapters, she will explain that she isn't suited to be a leader, she didn't have the capability in politics,unlike her sister who was smarter... She was simply a puppet that would be either be feared or respected by the citizens , a figure of strength that "would protect " the empire, so when shadow defeated her in a 2 v 1 combat, she was hell bent on getting stronger...