Frigga had no chance of winning from the very beginning.
In order to limit Watson's fusion ability, Frigga had painstakingly used the Primordial Demoness' power to break away from the human body and become an evil god at the starlight tier, and also set Antonio and Reid up and trapped them in the Elven Kingdom, which forced Watson to be unable to make a move.
Indeed, he was restricted to the point of being unable to make a move. However, there was no need for him to make a move. Baby Jeanne was enough to defeat Frigga.
Frigga boasted that the human heart was her most powerful weapon. However, she had never truly seen through the human heart. She thought that fear was the best way to manipulate the human body. It was true that people could be manipulated by fear. However, when humans were faced with an irresistible fear, they would display the will to fight instead.
Human history was the history of courage, and the hymn of humanity was the hymn of courage.