In order to ensure that the practice will have effect, Xiao Lin temporarily switched to a practice sword. It was not because he looked down on Cheng Ming, but because his Holy Soul Sword had been enhanced with Basic Swordsmanship. As a result, he would temporarily possess Basic Swordsmanship MAX. Meanwhile, Cheng Ming's Basic Swordsmanship was only LV7, which went up to LV8 with the addition of his Swordheart talent.
Xiao Lin would have an overall advantage in that scenario, but that would defeat the purpose of their practice. The main objective was to train with each other, not to draw a distinction between who was stronger.
Both individuals acted with decorum regardless of the heckling from the surrounding crowd. Xiao Lin neither activated his Miracle state nor used the Phantom Step, while Cheng Ming did not use any of his own skills either.