恃才傲物 To rely on one’s talent and look down on others. In the Book of Liang, the verdict on Xiao Zixian reads: “He relied on his talent and looked down on others. His posthumous name should be Proud.”
锋芒毕露 To show the full edge of one’s blade. Said of a person who likes to show off and outshine others.
韬光养晦 To hide one’s light and stay in the dark. To keep one’s abilities hidden.