There were no sounds as Legion-9 worked. His work was silent, as no hammer was striking against an anvil, and he wasn't actually using a heated forge or needing his hands for anything to make divine weapons. It was their altar that made the weapon for them.
They just have to give the altar instructions, such as the different steps of material combination, individual material ratio, temperature, duration of heat, density, and shaping. Each of these instructions affects the outcome of their product.
They haven't found the necessary material ratio to mix divinity gold with the other raw materials or the steps needed to combine them, which is causing them to fail at creating a superior product with the more powerful material. But by eliminating the other materials and focusing on divine gold, they have removed the need for different steps of material combination and ratio of combination.