danmachi overpowered

It's extremely overpowered! The abilities showcased in the manga give the protagonist a huge advantage and make the story quite exciting.

Maybe it has the ability to absorb chakra. So when Naruto is in a fight against an opponent with a large amount of chakra, he can use the sword to drain some of that chakra, weakening the enemy while strengthening himself. The sword could then store that chakra for later use, like to boost Naruto's own attacks.

It could be a sword that can cut through any substance, like the Susanoo easily. Just imagine Naruto swinging it and slicing through powerful jutsu defenses as if they were paper.

Well, it really depends on the specific fanfiction. Some fanfictions do make Ichigo overpowered. They might do this to explore different storylines or just for the fun of it. For example, in some, he could have a sudden boost in his reiatsu that makes him almost unbeatable. But not all fanfictions take this route. There are also those that focus on his character development in a more realistic way within the context of the Bleach universe and don't make him overly powerful.

Yes, it is. The story has reached its conclusion in the manga.

Yes, the Danmachi novel is over. It completed its run with a well-developed plot and closure for the characters and their adventures.

Yes, it's over. The story reached its conclusion and there are no more new chapters.

Yes, it is. The storylines have been concluded.

Well, in some fanfictions, Naruto might obtain the overpowered sword through a mysterious inheritance. Maybe it was left by a powerful ninja from the past and Naruto discovers it in a hidden cave or something.

Another aspect is prior knowledge or experience. In some light novels, the MC is reincarnated or transferred from another world. Like in 'Konosuba', Kazuma has knowledge from his previous life which he uses to his advantage in the new world, and this knowledge combined with his unique skills makes him overpowered in certain situations.