The glow of the Truth Pendant signified to the masses that he was an alchemist.
If he got caught, according to Qian Cangyi's guess, he would definitely be beaten up first to let the masses vent their anger, and then be taken to the Central Square for alchemy clearance.
Plus, when Zate's alchemy was eliminated, Qian Cangyi was in the same room as him, and the Moon Ring Alchemist's alchemy was also eliminated. In other words, the soul link between Qian Cangyi, Qian Jiangyue, and Hawkeye 'might' not be affected.
Perhaps it was because the thing linking the three of them was an alchemical item, or it maybe for some other reason. Anyway, the three of them were still safe at the moment.
Following this line of thought, when Qian Cangyi was caught and taken to the Central Square.
Then, the leader of the Dark Truth would surely eliminate his alchemy and the way to determine this would be whether the Truth Pendant glowed.
