The Qing Emperor was exposed as a Great Grandmaster in the battle on Dong Mountain between chapters 125 and 155 of Joy of Life.

The Qing Emperor's identity as a Great Grandmaster was exposed during the battle of Dong Mountain in Joy of Life.
The Qing Emperor's identity as a Great Grandmaster was exposed by Sigu Jian of Dongyi. In the play, Sigu Jian had barged into the Qing Palace many times at night in an attempt to kill the Qing Emperor. However, he sensed the Qing Emperor's powerful zhenqi and could not defeat it. Thus, he had failed four times to barge into the Royal Palace at night. After returning, Sigu Jian held a press conference to announce that the Qing Royal Palace had discovered the world's fourth Great Grandmaster. He invited those who did not believe him to come to the Sword Hut to confront him. Thus, the Qing Emperor's identity as a Great Grandmaster was exposed in the show. The specific time of exposure was not explicitly mentioned.
In Joy of Life, the Qing Emperor's identity as a Great Grandmaster was revealed during the Battle of Dong Mountain.
The Qing Emperor was exposed as a Great Grandmaster in the battle on Dong Mountain between chapters 125 and 155 of Joy of Life.
The Qing Emperor's identity as a Great Grandmaster was revealed in the battle at Dong Mountain between chapters 125 and 155 of Joy of Life.
The Qing Emperor was exposed as a Great Grandmaster in the battle on Dong Mountain between chapters 125 and 155 of Joy of Life.
The Qing Emperor was exposed as a Great Grandmaster in the battle on Dong Mountain between chapters 125 and 155 of Joy of Life.
The Qing Emperor's identity as a Great Grandmaster was exposed during the battle of Dong Mountain in Joy of Life.
In Joy of Life, the Qing Emperor revealed his identity as a Great Grandmaster in the chapters between chapters 125 and 155.
In Joy of Life, the Qing Emperor revealed his identity as a Great Grandmaster in the battle on Dong Mountain between chapters 125 and 155.