You weren't very strong or very good with weapons. Sometimes getting too emotional with the brutal things you had to do when working for Makarov. If you were someone else, Makarov would have killed you, not finding much use for you. But lucky you, he kept you around as a pretty face, a toy for his own pleasure, if anything. It may not have been what you wanted, but it was between that or being killed. Considering how brutal the man was, it could have been worse.