There isn’t much description regarding his appearance in the book.
Jarrett and Xaden are fighting over a pass. There is only one pass available for lieutenants during that weekend, and Jarrett has it. Xaden want’s this pass so he can see Violet for one day, leading to their intense and serious fight.
Jarrett swings at Xaden twice, but misses each time. In response, Xaden delivers two powerful punches with full force, knocking Jarrett down to his hands and knees on the dirt. Blood drips from Jarrett’s mouth as he hangs his head, trying to recover from the blows.
See also Lieutenant Colonel Degrensi’s rule.