Can be achieved just after the second boss. Go though the newly opened gate, kill the enemies, arrive at a locked gate and notice a path off to the left. Near start of this path is a woman carrying a large hammer. You can talk to her with
. Do so and exhaust the dialogue, at which point she'll offer her services to upgrade your weapons. It's highly likely you'll have the required rank 1 steel items to upgrade your weapon, or the rank 1 leather to upgrade your armour, so go ahead and upgrade either for the achievement.