Xu Feiniang's initial Flying Sword Transmission was for the Fiery Fire Ancestor, not for Shi Nanxi. She merely described the situation in Mingyu Immortal Market in general terms, inviting him to come and see for himself.
As for how many Sects would be involved, the Fiery Fire Ancestor would calculate it himself; being a junior, Xu Feiniang was in an awkward position, and speaking too much might be detrimental.
Shi Nanxi only knew that Shi Feiyang had killed One Light Master, but according to their calculations, One Light Master was destined for Heavenly Punishment; Shi Feiyang merely took the opportunity to strike when he was already down at the last moment.
From his perspective, only the grand battle at Yuan River truly demonstrated Shi Feiyang's formidable power, but he had no intention of challenging Shi Feiyang head-on.
