Sima You Yue opened the book titled, Raging Inferno Blade. She saw that the title was Black levelled Spirit Skill, and it wrote that anything other than a Spirit King would not be able to learn it.
"It's actually a Black levelled Spirit Skill!" Sima You Yue called out with surprise, "However, I have to reach the rank of Spirit King in order to be able to cultivate it. Right now, I am only able to read it. I never thought that Grandfather would actually be in possession of a Black levelled Spirit Skill, no wonder his strength is so great."
When a Spirit Lord first began, he could only depend on absorbing and condensing Spiritual Qi as a method of comparison. Right now all they were able to do was to condense tiny little spheres or drops of whatever. If one wanted to increase in strength, they had to use a Spirit Skill.