If memory serves MC was not a terribly good fighter but was a good tactician. Saves the queen of a kingdom... feel like I'm getting senile at this point, lol. It may have been isekai, mc often used ability to alter fortifications and structures during a war, upgrade hardness of walls, make weapons better, it's NOT Upgrade Specialist in Another World, but was similar in concept ability wise but on a more... broad usage (entire buildings, structures, etc) uses it to remove half a building during a war to expose enemy, etc. Def a unique cheat ability for mc.
A VIP as Soon as You Log In - has some similar elements but it's been a while since i've read it so i'm not sure. I do recall him reinforcing/building walls and siege weapons etc.
Just checked that one, that's not it, to be entirely honest, I'm not sure if I was reading KR/CN or what exactly at the time even... and I'm really batting zero on finding it. Usually don't have huge issues refinding stuff I read before, but man this one is vague and even going through the tags I'm getting no where.
It could be World Customize Creator. Isekai, with a guy who’s the “Evil God of Calamity”. Built towers, reinforced/upgraded weapons, and could make duplicates of stuff that was hard to make normally. I think he fixed a mutilated corpse during one of his outings, it was crushed or something so he put it back to its original form. I do remember there being a queen from another country, but I don’t remember him saving her.
Thank you, got caught up in another novel for a bit and didn't make it back to look again after the first response, I am pretty sure it is "World Customize Creator" after looking at the first few chapters.