Xue Ren, as Lord from demonic race thought, doesn't have one identity. He, due to his talent in 'Sword' has gotten himself quite high position in the Salus Empire which has quite easy and nice system.
Royal family and four clans.
That's the main powers here, and Xue Ren had chosen to join one of the four clans using his sword. If Red Spear is the epitome of Black Devil, then black sword is the weapon of 'Heartless Swordsman'. Such nickname perfectly describes Xue Ren who simply doesn't give a fuck about anyone here.
After growing and spending time with his maids, the cold barrier around his heart obviously got shattered which caused Xue Ren to open himself for them to the point where he feels guilty of having thoughts about sarcificing them in upcoming war.
He has come here to fuck up demonic race and take their resources without much thoughts after all.