Hmmm, two clues that is badly presented and plays a role in story. But, I don't want to spoil anything so I'll only write what I know it is missing or not presented well.

When QC hits that ghost with lightning (here attack was wrong), he spills more beans as he says "you again? 18 years ago you disturbed me and now again?". This tidbit should give enough to understand much more.

Also, that demon faing QC after... it is because he touched sword after sword absorbed that ghost. That was vision produced by sword

These two clues are introduction into story about his origin. As I said this novel always has more than one arc running simultaneously and this is for arc 4

This breakthrough shattered the formulaic tropes. I was always invested in the supporting character for how much he hated his fate. He had dulled over the past few arcs. This episode has been very rewarding for him, similar to a MC. Hope to see QC meet similar adversaries (rivals) in the future.

Pretty much all side characters lose most importance after mortal arc. They still show up for few chapters in starting divine realm and completely get forgotten in ending parts of divine realm story. The only one who can follow him a bit is You Qianxue, but even she gets left behind because of level disparity. In outerworld they are completely absent and it is doubtful they will come to supreme divine realm

Except, this is far from bad. MC changes for better, he gets cocky lone kind of sadistic cowboy instead of goody two shoes who is constantly rescuing family and friends.

MC's gotta shine. But they did justice to this character is what am saying. I had frankly lost interest in this one for the past 3-4 arcs ever since he too Heinu to that black swamp things have been monotonous. Now it's getting good again.

Now many side characters will also rise. Can’t wait for the next episode.

Dope, that G about to be a sword God

XDD

Why the ancient floating arena arc reward was parasite seeds? They wanted to harm them?

Well it gives a lot of benefits but they didn't know that it would cause you to turn into a demon. Doubt many people got to that far into their cultivation for the seed to bloom/reach that point.

so those parasite take bodies of it's host?