Can sense death: Yes.
Visible cause of death: He was killed in battle and bled to death on the floor. His injuries were a result of magic and sword - imagine his black splotches are mostly around the torso, with a large mass of black around his throat and in his hair. IDK how you'd interpret magical wounds so feel free to get creative. Actual canon detail is in his app.
Command level: N/A unless it's to get him to calm down or something.