There's no need to guess; Chen Guan already knows who this man is.
Xiu Jie Ming, the most promising young leader of the Xiu Family's next generation. Although he is not as famous as Jiang Qiemo, that's because he comes from a military family, which is somewhat different from those born into wealthy and noble families.
Real military families do not flaunt their martial prowess. Being able to lead a team to victory is their greatest honor, while personal martial prowess is secondary.
"You all go prepare first; we'll head up the mountain in a few days," Xiu Jie Ming instructed the others to leave, leaving only Chen Guan and Xiu Yingmei standing there.
After everyone left the main tent, Xiu Jie Ming looked at Chen Guan and asked, "Are you Chen Guan?"
"Yes, Commander, I am Chen Guan," Chen Guan replied according to military protocol.
"Good, then go die." Xiu Jie Ming, without missing a beat, drew his sword and slashed at Chen Guan, the blade moving as fast as a flash of lightning.