Metaphor of pen sharpness.
The source of the idiom: Guo Ruoxu of the Song Dynasty, "Pictures and Hearings - Zhao Guangfu": "He is a master of Buddhism and Taoism, and he is also an expert in horses. His pen is powerful and he is famous for his sword head and swallow tail."
Traditional writing: Knife head swallow tail
Phonetic: ㄉㄠㄊㄡˊ ㄧㄢˋ ㄨㄟˇ
Idiom grammar: as object, attributive; used in calligraphy, etc.
Emotion.Color: Neutral idiom
Idiom structure: Combined idiom
Era of production: Ancient idiom