Han Mei, the true original owner, didn't interact with Wei Chaoran. Chen Luoyang's clone, Daoist Banhai, could freely use the Wind Thunder Mystic Stone in his hand to trade with Wei Chaoran, while his true body didn't need to come to the front of the stage.
At the moment, it was better for him to ensure that no one suspected the relationship between Daoist Banhai and Chen Luoyang's main body.
As for splitting the Wind Thunder Mystical Stone into two, Chen Luoyang had only shown half of it to Wei Chaoran today. It wasn't that Chen Luoyang was afraid that Wei Chaoran would renege on his debt or that he was worried that Wei Chaoran would have thoughts of snatching it on the spot.
The main reason was to give Wei Chaoran a sense of security and give him the impression that the Half-Sea Daoist was apprehensive.