There was a man named Jiji of Song Dynasty.
A piece of cold star iron that could forge a magical weapon and cause strife in the world, but it happened to fall into the hands of the crazy Song Jiji. This iron was cast by the blacksmith Song Wanyang, but it was not a sword, let alone a knife. It was cast into a scale beam as if by God's will.
Song Jiji held up this seemingly edgeless "fair scale" to weigh the rights and wrongs of the world and measure the weight of people's hearts.
Perhaps this is the simplest truth to call the rivers and lakes.
Purpose: Jianghu needs a steelyard