Mitch didn't quite know what to say as he glanced at Ryuzaki when the detective spoke up. He wanted to agree with L - couldn't there be something else in that book without the life or death consequences? - but on the other hand, he also didn't want to undermine Blythe's confidence. There had been no book for Mitch on what he could and couldn't do, and he still didn't completely understand his own powers. That didn't stop him from experimenting, from learning by trial and error.
"It's up to you, Blythe," he said. "Ryuzaki's got a point, but... I trust you. If this is what ya wanna try, go for it."
He already knew that Blythe was so much smarter than he was. If she understood what she was doing, then all she needed to do was try. If she wanted to try something else, then that was perfectly all right too, and Mitch figured nobody here would think less of her for that.