Selena didn't charge at Michael when he finished the Curse Fusion. It was a delicate task that required Michael's entire attention.
Of course, staying idle for several minutes in real combat wouldn't be possible, but it was fine for the first attempt. Michael had to get used to the Curse Transformation first. Only after getting used to it would he be able to complete the Curse Fusion faster and without any issues.
The difference between the Curse Transformation Arts and Curse Fusion was that the former was a technique while the latter was the corresponding effect. Usually, Curse Users wouldn't call their transformation Curse Fusion, but it was more commonly used for Curse Users with multiple Curses. Under normal circumstances, their Curses would clash to gain more control than the other.
