Qibaodao 七寶刀

In Chapter 4 of the Romance, the Minister over the Masses Wang Yun, who has received a secret letter from Yuan Shao but has no plan, gathers the high ministers at his home on the pretext of his birthday and weeps in lament over Dong Zhuo's tyranny. Cao Cao, Colonel of Valiant Cavalry, who laughs at the gathering, says that he has bowed to serve Dong Zhuo in order to seize a chance to do away with him, and that he has heard the Minister owns a seven-treasure blade; if Wang Yun will lend it to him, he will go into the Chancellor's residence and stab Dong Zhuo to death. Wang Yun personally pours wine and offers it to him, and when Cao Cao sprinkles the wine on the ground and swears an oath, Wang Yun hands him the precious blade. Romance, Ch. 4 §23–27

The next day Cao Cao goes into the Chancellor's residence wearing the precious blade. Dong Zhuo sends Lü Bu out to choose a fine horse that has come from Xiliang, and when, after Lü Bu has gone, the corpulent Dong Zhuo lies down facing the inside wall, Cao Cao draws the precious blade to stab him. At that moment Dong Zhuo sees Cao Cao reflected in the dressing mirror, turns around and asks what he is doing, and Lü Bu has also arrived outside the pavilion leading the horse. Romance, Ch. 4 §28–30

Flustered, Cao Cao holds up the blade, kneels and says that he has a precious blade to present to His Excellency. Dong Zhuo takes it and sees that it is a little over one chi long, inlaid with the seven treasures and extremely sharp — truly a precious blade — and hands it to Lü Bu to keep. Cao Cao unfastens the scabbard and gives it to Lü Bu, then, saying he would like to try out the horse, leaves the Chancellor's residence and flees to the southeast. Lü Bu says it looked as though Cao Cao had meant to stab Dong Zhuo and presented the blade when he was discovered, and when it is learned that Cao Cao has slipped out through the east gate, Dong Zhuo sends dispatches everywhere ordering his capture. Romance, Ch. 4 §30–33