Otherworldly SurvivorG 55

There is a total of 103 weapons in the game. You can check if you already forged a weapon in the blacksmith menu with the presence of a little green star icon at the lower right part of the screen.

To make this achievement less annoying, you should carefully visit every part of every map and beat every enemy on your path during main story to collect a very large set of materials. The very last weapons need materials from the optional dungeon visited during Otherworldly Visitors side quest :