I've been re-reading the first book and Kaladin keeps going back to what his dad use to say.
“My father used to say that there are two kinds of people in the world," Kaladin whispered, voice raspy. "He said there are those who take lives. And there are those who save lives."
This has strong sense of foreshadowing to me since Kaladin believed that sometimes you needed to take life in order to protect life.
I believe that his Fifth Ideal might be something along the lines of "I will protect without killing."