Worse in ds3 imo. Gotta do a bunch of runs to find rings and also get materials for the weapons there. Least once you figure out what to get on the first run, you can just repeat the other 2 times for the rest of it
I have also collected all weapons and the trophy will not come. I ckeck the list 10 times. The only difference is that I upgraded the moonlight sword, dragon sword and nitoh greatsword full. I try to get them again and hopefully this was the reason.
I am working to this achievement but some of the other "annoying" achievements like collecting all miracles was not popping up for me. I did some searching and people have had this same problem. They either put everything into the bottomless box and then re-put everything back into their inventory and if that doesn't work then while having every weapon in your inventory drop one of the items and re-pick it up and it should pop up. Hopefully that helps cuz that's a terrible achievement to get stopped on like that.