You guys surprise me... are we reading the same story?
No fight was skipped! It was fought to the conclusion, and Noh got knocked out while finishing it.
It was obvious long ago that the "Demon God" aka "something that isn't supposed to be here" (hence the extraction of that girl pretending to be a male soldier) was this him
The fact that they're now referring to the "Metal Demon God" (metal is hard) even confirms it further.
What they didn't show was the after fight with everyone dead or knocked out. I can speculate pretty easily there who found Noh and clean up after.
He was already going to deal with the situation, but it had already been resolved. He would have found Noh - who his son already told him about - and who (to his surprise) survived the fight against the "Demon God". Did the "Demon God" survive the fight? Unknown... but if so he likely got cut down shortly thereafter by this gentleman. Finding Noh alive though, he carried him off and treated him.
Possibly I'm wrong (if there is a connected novel, I haven't read it), but I think I'm likely to be correct. It doesn't seem that hard to figure out.
edit: I assumed the images where cut into much smaller parts than they really are, sorry. I'll use a spoiler tag to shrink my post. You should still figure out who I mean...