Hammer in her left hand, sword in her right, the eldest sister is connected to both worlds.

The female protagonist was a demon in her past life, not a good person, and sometimes quite ruthless. She's a weapon refiner, there's no romantic pairing, it's an ensemble piece. The female protagonist possessing a little beggar is foreshadowing. It's not about bullying anyone! (Demons are demons, their conflicts are irreconcilable.) The river of time slowly flowed, eventually casting Xue Lan, this old demon who should have died long ago, out of the story. Through a series of coincidences, she successfully possessed someone and joined the Xuanhuang Sect, becoming the senior disciple of Jiyuan Peak. While her master taught her magic, she forged blacksmiths; when her master went down the mountain, she went into seclusion. When her master asked how her training was going, she replied, "Master, I'm out of money for weapon refining again." Until Xue Lan was approached by something called a system. The system existed in a book world sharing a common worldview...