chapter 95:

"Remember, don't let your anger be the fuel to your power. It will lead to your own destruction."

Day two of Leo's training with Grim. Grim would always tell him that line. Don't let the agitation rule his other emotions over and control him. Leo's morning begins with Grim's lessons. He would talk all the time, about how to control his emotions and how he should fight a stronger opponent. Not only he was teaching Leo mental strengths, but also he was pointing out Leo's mistakes when wielding his sword. And also the way he dodge the attacks. He pointed all of that out and lectured Leo even more. He was rushing him, he knows. But that was because his time nearing to its end. He needs to teach him all that he knows before he rest in peace. It has been so long.