He was willing to tell Duan Gujin everything he knew because he had previously seen Duan Gujin completely subdue an enemy who could control Blood Crows with a single Dark Weapon, turning the enemy into his slave.
Wu Zian didn't want to end up controlled by Duan Gujin's Divine Soul like the Blood Crow Demon, becoming a walking corpse.
Once he was truly controlled by Duan Gujin, the latter would definitely make him reveal everything he knew.
Weighing the pros and cons, Wu Zian felt that since he had sought out a skilled warrior like Duan Gujin for collaboration, there was no need to hide anything.
If they had to look for the treasure with someone else, they might not trust that person.
The reason they chose to search for the treasure with Duan Gujin was that they had witnessed his prowess before, knowing that he alone could defeat an assassin at the Martial Sect Realm.
