Achilles: Legends Untold

This is story related. You will have a quest to help Lysander, which is given by the Blacksmith apprentice. Once you complete this, you will then go to Desecrated Ruins, North of the Fisherman's Nook Shrine. In here, defeat the Scorpion. Its not that hard, and a solid weapon will suffice.

Once you return to finish the quest, you will be told to head to the new Blacksmiths west of your location. Head inside, and you will watch a short cutscene, where the achievement will unlock.