The nangseon was a branched spear

Spear

A spear is a pole weapon consisting of a shaft, usually of wood, with a pointed head.The head may be simply the sharpened end of the shaft itself, as is the case with bamboo spears, or it may be made of a more durable material fastened to the shaft, such as flint, obsidian, iron, steel or...

 with many thorns attached to the branches. It is also called 'multi tip spear'. The blades could be dipped in poison. The nangseon was a perfect weapon for defense. It would be difficult for the opponent to get near the person holding the nangseon without getting touched by the thorns. The nangseon is already being mentioned in the 16th century martial arts manual Muyejebo

Muyejebo

The Muyejebo is a Korean martial art manual written during the reign of King Seonjo in 1598.-History:As the Imjin war dragged on for years, Korea needed a way to effectively train a large number of troops, and the Korean military adopted a training methodology based on a Chinese military manual...

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The weapon was probably an invention of the Chinese general Qi Jiguang

Qi Jiguang

Qi Jiguang was a Chinese military general and national hero during the Ming Dynasty. He was best remembered for his courage and leadership in the fight against Japanese pirates along the east coast of China, as well as his reinforcement work on the Great Wall of China.-Early life:Qi Jiguang was...

 (戚继光) of the Ming Dynasty who describes it in his manual titled Ji Xiao Xin Shu

Ji Xiao Xin Shu

The book Ji Xiao Xin Shu was written by the Chinese general Qi Jiguang of the Ming Dynasty. The title can be translated as New Book Recording Effective Techniques....

 which served as an example to the Muyejebo. The nangseon acted as the backup up of the shield (deungpae

Deungpae

The Deungpae is a shield made of wisteria and bamboo which was used by the military of the Joseon Dynasty. The earliest Korean description can be found in the Muyejebo.-Use:...

) bearers in a Mandarin duck formation.