You can play the game more than once, no one said you
had to get all the achievements in one go. Must be such torture that you have to play and enjoy a game a second time at any time of your choosing to get an achievement that you can get on any playthrough

But yeah, I don't know why the rueful axe wasn't counted but I'm not very knowledgable of a lot of the lore. Same thing happened to you as with me; svcks but, oh well lol. I really enjoy the game so I can play it (at least) once more.