I have a sword. What is the noumenon of Er Ya?

What do you want to ask is what is Er Ya's exclusive sword? A spirit beast. According to official website's query on "A Sword Alone", Er Ya is a kind of spirit beast with high physique and strength, and is one of the partners of the protagonist Yang Ye. In the novel, Er Ya is interrupted by her double horns in order to help Yang Ye fight against the fate of a plain skirt woman.