A new student with a powerful Semblance

Duke was a new student who had recently come to Beacon to learn to be a Hunter. While not the best at combat, he had a Semblance that could make him powerful.

The Semblance was called 'Master of the Mind'. Basically, all he had to do was touch the forehead of any person (or Grimm) and he'd have full control of their minds. He could input commands mentally or verbally, and whoever he was controlling would obey the commands until he released control via pressing their forehead again.

But why test this on Grimms when Beacon was full of sexy women who deserved a Master of the mind?