Compared to Zhao Sheng, Zhao Xuanjing didn't need to go through such trouble. The secret scrolls within the Ksitigarbha Sect contained far more detailed information than Zhao Sheng knew.
Put simply,
If nothing unexpected happened, this Great Chi Jian and the Blood God's Son that possessed it were indeed the main culprits behind the great war between the two realms that occurred in the past.
When the war between the two realms broke out that year, these two culprits suddenly disappeared without a trace, never to be heard from again.
In addition, according to what he knew, the Blood Demon Sect that had been stirring up trouble for the last seven to eight hundred years and proving difficult to eliminate was the handiwork of that Blood God's Son.