The first fight where the MC actually used a proper tactic, instead of pure ass pull. Too bad the demons indeed were bottom of the barrel losers, so it was kind of meaningless. Still, what says all the demons aren't like that? They have had a thousand years of peace, where the demons could basically play with the humans as much as they wanted, with the humans only growing weaker and weaker. That doesn't cultivate strong demons either. It seems to me the MC is going through a lot of work for no reason whatsoever. He could actually go out and crush the demons at leisure. Perhaps he's just playing it safe by having the kingdom under the barrier, so that no demon will sneak behind his back while he's performing a nice little demon genocide out there. Though it seems to me the humans could already defeat any stupid stray demons that might think of risking everything by attracting Matthias's attention. Any smart demon would instead try to hide the best it could.
I was pleased to see the pervious chapter was misleading and there were female demons involved.