C60 Two of the Tiger Cub's Words

He may be silent in the Pingqiu Valley, but as charcoal makes coffee and continues to work with the Blue Witch, I still saw him take out a skill book from his hand and use it. I don't know what skill he learned. A skill book that can only be learned at level 28 shouldn't be a shocking skill, right? I hope that it can be used in the future to save his life when fighting a boss