The reason why Wen Qing took the task of being the Divine Forger was that she needed to create a weapon with super high damage to cover up the fact that she had a high attack power.
The hidden task was not easy to do. Even with the additional luck, she still needed to spend a month to complete it.
The reward for completing the task was to get the title of Divine Forger, but she had to make a Divine-level weapon first. What Wen Qing made was a dagger. She had high agility and to attack someone in secret with a dagger would definitely take them by surprise.