The Legend of Qin - Season 2 Episode 13 Broken Rainbow, the Taboo

Tianming somehow finds the way to transform Feigong into all kinds of weapons. Gongshu Chou operates the machines and traps the three children, but himself is also sent into the prison that Tianming and Yuer falls into. Gongshu Chou claims to be a friend of Master Ban. He tells Tianming about the sword painted on the ground, the Broken Rainbow. This sword was the one Jing Ke used to assasin Ying Zheng. After Jing Ke died, Ying Zheng Broken Rainbow reforged as Rainbow Abyss and granted it to the person who killed Jing Ke. Tianming is shocked to know Ge Nie has killed Jing Ke.