I just came from there. Wouldn't have discovered this if I didn't saw some post over there. Seems like it is related after reading the 1st chapter. Reincarnation maybe? If that's the case then I can understand his possessiveness of his Sheath when he became the older one.
Wait so is Yue the reincarnation of his past self or does he Only resemble the master’s Old Sheath in Zhu Zi Zhi Jian ( Prequel to Temper )
I dunno, feels like he's the same guy but reverted... in the next chapters that guy's personality will return