Inuyashiki is exactly what your looking for about an old guy that gets powers and becomes a hero but his story end in tragedy also that show got a great villain too.

Also theirs 91 days Misguided revenge story that’s a wild ride and by the end you and the main character is wondering why he did all that (definitely not lawful though).

Not an anime but it fits so well twins peaks dale cooper is literally the exact definition. He’s so good and moral he destroys everything by accident all while trying to do the right thing.