Tataka said it was possible to improve the Noble Siel's Supreme Bow, and told you what he would need to do it. You obtained the Vorpal Essence, Special Shulack Refiner, and Blessed Aurium Ingot, and went to the Jotun Studio to fuse them together to create the Essence of Siel. You brought the Essence of Siel to Tataka, and he made a Siel's Dominant Bow.