The skill that Charles was going to teach Jung-Hwa was called "Dimensional Sabermanship" unlike realization swordsmanship that can block any attack, this skill will always hit your target no matter what.
Jung-Hwa's plan was to combine both Dimensional Sabermanship and Realization Swordsmanship together since they were definitely perfect for each other and since using saber is similar to using the sword it could be easy to combine both skills.
The training for this skill was all the training he did for the other 11 skills but 10x harder and so Jung-Hwa had to spend months working tirelessly to fully achive in learning this ultimate skill.
Siegfried cheared Jung-Hwa on as he did his training and they would have a sparring where Seigfried would use his whole strength and adding onto his depleted energy, Jung-Hwa had a hard time to fight Seigfried.
Jung-Hwa was able to defeat Seigfried no matter how tired he was after three months of sparring with him in his exhausted state and Charles was extremely impressed since he already acknowledged Seigfried.
But Jung-Hwa was able to spar with him and win in his extremely exhausted state, Jung-Hwa had a few breaks here and there and Jung-Hwa decided to give Seigfried the greatsword he made for him.
It was a good cover up that it was a thanks for helping him in his training and Seigfried absolutely loved how the greatsword felt in his hands, Jung-Hwa knew he would love this since he was the one who wrote he loved that sword.
So Jung-Hwa was pretty happy that he was able to give Seigfried his main weapon in the novel and then after a little while Jung-Hwa remembered that he took something from the God Of Theives as well that was supposed to be for Seigfried.
It was a necklace, it didn't do anything but just had the initials SF on it but as no one could find any use for it, it was deemed useless and no one wanted it until Seigfried found out that it was a necklace from his mother.
So Jung-Hwa tried to slowly bring up him finding a necklace with the initials SF and showed it to Seigfried and asked, "I found this necklace a few months ago and it has SF on it and your name reminded me about it, do you know anything about this?".
When Seigfried saw this he was in shock since in the story that Jung-Hwa wrote, Seigfried lived with his mother until they were being hunted down by the enemy kingdom and he remembers that she had a necklace.
Then Seigfried realized it was the exact same necklace of his mother when Jung-Hwa gave it to him, Seigfried hugged Jung-Hwa and thanked him for bringing it back to him.
Jung-Hwa suddenly remembered what he wrote for the original story, it was that the main villain of the story used the necklace into tricking Seigfried that his mother was still alive and he was used until he found out about it.
So Jung-Hwa was really happy he got this before, Jung-Hwa also wrote in the story was that the God Of Theives would help Seigfried throughout the story until Seigfried realizes that he knows his mother.
But Jung-Hwa didn't want to tell Seigfried everything since he might get suspicious because it would raise the question about how did he know about the God Of Theives' hidden stash.
So Jung-Hwa told Seigfried that he found it in an old store and he felt like he had to buy since it felt like his instincts wete telling him to buy it and Seigfried thanked him once again for finding his mother's necklace.
Then immediately after that Charles became even more strict in Jung-Hwa's training because he truly wanted someone to be able to learn his skill so it won't just end with him without him passing it on.
After another three months Jung-Hwa was able to create a small hit no matter what, Charles saw this and asked Jung-Hwa to try it on him, so Jung-Hwa faced to the side and tried stabbing forward.
It immediately showed up as a hit towards Charles and he was extremely happy that Jung-Hwa was able to learn his skill and it didn't have to end with just him but Jung-Hwa knew in the original story it wasn't like this.
Charles would've died to one of the villains that targeted Seigfried and he wasn't able to pass it on but Seigfried promised that he would try to learn it anyway possible and he was able to learn a similar skill.
It wasn't as strong as Charles' skill but it was able to hit an enemy from far away, the skill would create an aura in a shape of a sword and it would act like projectiles and it would deal a significant amount of damage to an enemy.
But now as Jung-Hwa learned the skill, Seigfried might not be able learn the skill so Jung-Hwa decided that he would help him to learn the skill or at least the dimensional sabermanship skill since it was his fault for making him a bit weaker.
So Jung-Hwa asked Seigfried if he wanted to try and continue learning the skill and with a little persuasion from Jung-Hwa, Seigfried quickly agreed and then the two started training together.
Jung-Hwa knew that learning the skill might take long since Seigfried wasn't as fast in learning as him because he didn't have the system but it seemed like Seigfried was doing great progress in learning the skill.
But again he wasn't close to creating the same skill from Charles but Seigfried was starting to create a sword made out of aura and it seems like Jung-Hwa forgot that Seigfried was this talented in using any sword.
Then after just less than two weeks, Seigfried was able to learn his version of the dimensional sabermanship and he named it the same name that was used in the novel, "Projectiled Aura", it was a really strong skill.
So Jung-Hwa was contemplating if he should learn it or not but Jung-Hwa just decided to let it be Seigfried's own special version of the skill since it might motivate him less if Jung-Hwa learned it that quickly.