I want to say Mousetail...Or Shrewpelt? I don't think either of those are right... It's been so long since I've read the series. Is this cat from Power of Three? Or A New Prophecy? I think a clue like that would be awesome.
I rejoiced when I became an apprentice before Six moons In a fight, I was killed My mentor gave me my warrior name Then he chose to never train another Before six moons