Complex sentence: Alp Arslan, who took great pride in his reputation as the foremost archer of his time, motioned to his guards not to interfere and drew his bow, but his foot slipped, the arrow glanced aside and he received the assassin's dagger in his breast.
Split into simpler sentences: Alp Arslan, who took great pride in his reputation as the foremost archer of his time, motioned to his guards not to interfere. He drew his bow, but his foot slipped, the arrow glanced aside, and he received the assassin's dagger in his breast.