Tarzan, Lord of the Jungle by Edgar Rice Burroughs

Down the field thundered the two chargers. Silence fell upon the stands. They were almost met when Sir Guy realized that his adversary bore no shield. But what of that? He had been sent into the lists by his own people -- the responsibility was theirs, the advantage Sir Guy's. Had they sent him in without a sword Sir Guy might still have slain him without besmirching his knightly honor, for such were the laws of the Great Tourney.

Yet his discovery had its effect upon the Knight of the Sepulcher as just for an instant it had distracted his attention from the thought that should have been uppermost in his mind -- gaining the primary advantage by the skill of his opening attack.