What kind of weapon is Fenshui Emei Thorn? Seek to explain.

fenshui Emei thorn is a short double weapon, a kind of Emei thorn, also known as Emei thorn or double front thorn. About one foot long, thin at both ends and thick in the middle, the head is slightly flat, diamond-shaped and pointed. There is a small hole in the middle of the sashimi, with an iron nail riveted on it. The nail can rotate flexibly in the hole, and there is an iron ring underneath the nail connected to it. The weapon is petite and suitable for fighting in the water. It can be used for assassination in the water or for diving into the bottom of the water to dig through the bottom of a ship, so it is called Fenshui Emei Thorn. This is the weapon used by Fan Jiangshu in Seven Heroes and Five Righteousnesses.