I have no idea what it was they were looking for. They did mention keywords, but it was, in general, down to what they called exceptional essay answers.
I spent a lot of time thinking about the qualities of a pilot and moulding my answers to fit those competencies. I also think part of it is down to your background as well, or your interest in aviation, what you studied, whether you've flown an aircraft before, etc. Think about what you could do to make yourself stand out when developing your answers, what have I done, or what can I do to show the airline why I deserve a shot?