"That's enough," declared Miss Leywin as the three cadets finally dropped their guard.
Blood trickled down Stella's face, a result of the punch that nearly knocked her out. Chase struggled to stand on his right leg, and Isaac's body still shook from the attack he had blocked.
"At least we were finally able to hit him," said Chase as he gazed at the dissipating smoke cloud where Delta had been.
Yet, as the smoke dispersed, Delta appeared, standing a couple of meters away from where Chase and Stella had held him, completely unscathed, though his clothes bore slight burn marks.
"H-how?" Isaac blurted out in disbelief.
"That's all for now, Delta. You can leave," Miss Leywin instructed.
"Thank you for your time," the three cadets said, bowing their heads.
Delta walked out of the ring, bowed to Miss Leywin, and left the gymnasium. Once he disappeared behind the door, Miss Leywin turned to the three cadets.
"Well, that was quite disappointing. You still weren't able to land a single hit. Not only that, you were outclassed by Delta even though there were three of you, and you possessed more raw power, speed, and ability control than him. At least you were able to damage his uniform slightly."
"I don't know how he could've taken that attack head-on and still get out unharmed," Isaac said.
"That's because he also outsmarted you."
The three cadets looked confused.
"You were so powerless against him that he didn't even bother to show the full extent of his ability. What did you notice about the properties of his barriers?"
"We were able to destroy them with just our physical attacks," Chase replied.
"Such a simplistic mindset has no place in the Black Guard. Make the effort to actually make an analysis."
"Considering the lower stage Delta was restricted to, the barriers had high tensile and compressive strength with little to no ductility. The barriers were rather stiff and brittle, which explains why they broke in a glass or ceramic-like manner," Stella analyzed.
"Very well, anything else?" Miss Leywin waited a couple of seconds for one of them to answer, but the three looked confused. "What about the roughness of the barrier, for example? What other properties can you think about?"
"It had a low coefficient of friction," Chase answered, and the three of them realized what Miss Leywin was trying to convey.
"Seems like you all got it now. You were so desperate to keep up with Delta that you didn't even bother to question what was the extent of his ability. You just assumed that his ability allowed him to create barriers and control their strength when, in fact, his ability goes beyond that."
"He's able to control several properties of his barriers…" Chase muttered.
"Exactly. Coefficient of friction, absorbance, flexibility, elasticity, electrical conductivity, and thermal conductivity are just some of the properties he's able to control with his ability," Executioner Leywin looked at Isaac, "You are right. With the restrictions he had, he wouldn't have been able to get out of that attack undamaged if he took it head-on, so he didn't. The moment Chase and Stella teleported away, Delta drained all the energy in his body and redirected it to his ability. Then, he increased the dielectric strength, heat resistance, and conductivity of his barrier as much as he could while reducing the coefficient of friction to a minimum. He used the rest of his energy to increase the hardness of his barrier and placed it at an angle of 45 degrees respective to the energy beam. This way, he was able to redirect the power of the beam away from himself, avoiding any damage. He deflected the attack. It is important to say that draining one's body of energy is incredibly dangerous as it leaves you as defenseless as a non-awakened esper to any other incoming attacks. It would've been an extremely risky bet, however, due to Delta's extensive combat expertise, he knew his plan would work. Still, you were able to see some minor calculation mistakes as his clothes showed slightly burned spots here and there."
"But then, what should we have done?"
"There's not much you could have done with your current strength and skills. The only way to win the fight would've been to get stronger. There's an extremely important quality that an esper must have, and that is being able to grow in combat. Today's spar was to test just that, and as you could've guessed, your results weren't very impressive. The only one that showed some kind of growth was Isaac, whose energy beam got stronger during the first spar, and its activation got faster during the second one. But that marginal growth is not even nearly satisfying. Sure enough, growing in combat is heavily influenced by innate talent, but it is a skill that you need to develop if you want to become stronger," Executioner Leywin looked severely at the three cadets. Stella and Chase had their heads lowered, looking at the floor, while, on the other hand, Isaac was looking at her with shining eyes. What she had said about him had been the closest to a compliment that any of the three had received from her. Behind her blindfold, Miss Leywin rolled her eyes in annoyance.
"Well, seems like you are going another day without eating a proper meal," she said as she threw each of them some kind of energy bar, then she looked at Isaac, "Since you are the only one that showed some kind of growth, you may go to the cafeteria and take whatever little snack you wish. The list of possible choices has already been uploaded to your ID card. That's all; you may leave," she dismissed them.
The three cadets bowed, thanked her for the training, and headed out of the gymnasium.