True Monarch Xuantian, it sounds like a title for a Nascent Soul Realm cultivator. It seems not much different from that demoness, and compared to those Dharma Kings and Demon Lords, it appears somewhat lacking.
However, it's hard to say for sure. Huangfu Yi's family inheritance naturally knows the so-called various realms of the Taiji Realm, which intuitively affects only lifespan and is unrelated to actual combat power. Though theoretically, one learns as one ages, increasing the cap, and gaining more powerful divine skills.
