Give an example of a historical figure who misused philosophy.
To me, the most obvious example of a historical figure misusing philosophy would be Hitler. Hitler used philosophies (like those of Nietzsche) to justify his war of aggression and his genocide against Jews.
Hitler took, as the basis for his ideology, the idea of survival of the fittest -- the idea of life as a struggle for survival. This is similar to Nietzsche's famous dictum that anything that does not kill you makes you stronger. Hitler also took the idea of the superman -- the man who is not really subject to regular morality because of his superior will.
Using these ideas, Hitler put himself forward as a superman at the head of a super race. He used these ideas to justify his attacks on the Slavs to the east and his attempts at extermination of the Jews.