Shinari was a super capable of manipulating shadows with her will. She had various abilities such as teleporting into the shadow, summoning weapons with shadow, and so much more. She wasn't the first shadow manipulator however, she had seniors that taught her in the academy who also had control over shadow.
They had abilities that she had yet to master, and one of them was creating shadow clones. They said that creating a clone was the most difficult skill one could learn. It wasn't just creating and forming shadow in the shape of oneself, but one had to put the very essence of one's soul as well otherwise the clones would just be a moving objects without its own will.
With that hurdle, it was very hard to even create one clone, but Aldred effortlessly create three clones at once!
Shinari still could not believe her eyes as she processed the information. Aldred just did something she could only dream of doing, and that bring her self-esteem down a little.