Xie Feng's appearance began to change slowly since he obtained the Ring of the God of Destruction. More than change, it would be more correct to say that his appearance began to improve, going from an average appearance to above average. However, Xie Feng's mind was completely shaken when his appearance changed too abruptly just as he obtained the Pearl of Light.
If the change happened slowly, perhaps Xie Feng could still accept it and attribute it to anything, he would even look for a lame but sufficient reason to believe for himself instead of thinking that it was all because of a video game. But it was impossible for something like this to happen from one day to the next.
Now, on the flight from Shanghai to Beijing, when Xie Feng punched his fist against Mo Li's chest to test the armor's resistance, he was shocked and delighted to discover that his physical strength had practically doubled from what it was before!