What is the bow-adding equipment for the ancient scroll 5?

Ancient costume, you need to complete additional requirements to assassinate the bride. The dark elf girl will give a sapphire [coordinates] to find the snow-filled divination grandmother and get the position of the fortress. I found the old assassin behind a secret door. He was covered with an old cover.

Nightingale collection, obtained by the thieves' union, was later given a task.