In a different manner than Undine, it was hard to understand what Sekundez was thinking or feeling. She seemed like a spirit who didn't care much about anything, and that was what made things pretty complicated. But Leon felt a slight tone of worry from her voice... it looked as if she had some experience with that kind of dangerous action.
"Thanks for your concern, but this is absolutely necessary," Leon forced a smile while ignoring the headache. "Besides, it is just the beginning since I also have to train your skills, and I will need more mana to do so."
Most likely, that headache wouldn't decrease if Leon increases his mentality or endurance... because he was damaging his spirit directly by forcing it to obtain mana much faster than his current body can handle.
"Anyway, I guess it is time for you to explain what the skills I learned can do," Leon said. "Based on the knowledge, I will be able to focus on the most useful skills first."