The Seven-Star Precious Saber is the blade Cao Cao borrows from Wang Yun to assassinate Dong Zhuo in Romance of the Three Kingdoms. The weapon becomes crucial because a failed strike must instantly be disguised as a gift.
Chapter 4 names it before the attempt. When Dong Zhuo sees Cao Cao drawing the blade in a mirror, Cao Cao kneels and presents it instead. The text describes a saber a little over a foot long, decorated with seven treasures and exceptionally sharp; Lü Bu recognizes the attempted attack after Cao Cao escapes.
The saber marks the gap between intention and outward performance. Its rich decoration is explicit, but “seven-star” should not be expanded into celestial magic. The object is memorable because Cao Cao converts evidence of treason into a plausible offering in a single moment.