The ogre that hammered his hand against a rock resulting in its amputation couldn't kill him. The hundreds if not thousands of goblins he faced throughout his career couldn't kill him. Even the den of dire wolves he had faced in pitch-black darkness resulting in his face being permanently scarred couldn't kill him.
So how was it fair that it was a cough that was going to kill him?
Months before, it started small yet persistent. It kept him from his usual physical activity but in a couple of weeks, he was back to normal.
Yet as he got back onto his horse and pushed himself to attend to his life as usual, the cough would come back with a fury. He even found streaks of blood in what he was coughing up occasionally. He would simply discard his handkerchief and be on his way.