MC, destroyed a part of the estate: "Oopsie, I accidentally missed my lord's weakest knight because of my incompetence. Oh my, my lord you look upset, it must be that my rumoured incompetence has failed to satisfy your expectation of me being, as you described so intensely, a lying incompetent disgrace. Yes, I'm sure my lord who is so wise and powerful could do so much better than your weakest knight and what the incompetent me could ever achieve, please show us how true competence look like and then I'll resign from this knight job I was so definitely not pressured to take but ambitiously fought for! 🙃" (Just me imagining MC burns Argos' arrogance after all the insults, still hope that they could warm up later on though, he's the dad of the female lead(?) after all).
Also, in my mind of fantasy, maybe the spear was thrown at such a high speed that the spear disintegrated because it's used like a consumable offensive item for an energy blast, like Amarant's throw skill in FF9.