Although the body of Raiden Fu was identical to that of Raiden Ei, there were still some intrinsic differences. For instance, the body of the Raiden Shogun had undergone modifications, making it better adapted to the Musou Isshin to a certain extent. On the other hand, Fu's body was Raiden Ei's original, unmodified form, which offered significantly less compatibility with the Musou Isshin.
As for "Transcendence: Baleful Omen", although it dealt Electro damage in the game, in reality, it relied on the deployment of the Plane of Euthymia to execute spatial slashing combined with Electro damage.
However, Raiden Fu lacked the Plane of Euthymia, so she naturally had to develop a new skill. After all, this was not a video game where one was restricted to using a fixed set of abilities.
Chapter 44