These guys are Mo Yuntian's elite, the aces of the army. Their acknowledgment of Nie Yan as their instructor is a testament to Nie Yan's prowess.
Born into a military family, with his father as a soldier, Nie Yan inherited some of his father's beliefs. Subconsciously, he believes strongly in the supremacy of strength and is very dedicated to pursuing his own strength. Previously, Nie Yan didn't know what level he was at, as those he sparred with were just students, still having a gap with true fighters. But defeating Wang Duo today gave him more confidence; his prowess was already on par with the military elites.
Nie Yan increasingly felt the changes brought about by advancing to Shadow Dancer, wondering what secrets lay behind the Shadow Dancer title?
Unable to figure it out, Nie Yan decided not to dwell on it, focusing instead on doing what could be done in the present. He needed to train these thirty or so people.