Ending when nothing substantial is resolved is a terrible ending, no matter what. The premise of this was awesome, as blacksmith-centric things tend to be super rare (stories that are at least slightly interesting, anyway), but man was it squandered. All of his upgrades felt sudden, everything devolved into NUH UH and ending with the MC winning effortlessly, and the sudden asspull of him making a perfect replica of a holy weapon didn't feel deserved at all. If this was meant to get me interested in continuing the story in the light novel, it failed spectacularly. If the manga ended earlier before the harem got out of control, I would've been pissed that the story I was led to read ended up becoming this.
Once again, my hope for a dull series to get a decent ending is crushed. Wish authors and editors would stop making bad endings and cliffhangers.