This is based solely on the anime. I am completely aware of his transformation later in the manga...

There are many, many people who truly believe that Raki is useless... I am not one of those people.

If Raki saved Clare's life and is her only purpose to live (besides killing Priscilla), how can he be considered useless? I admit, he's extremely annoying at times, but he's not useless. He represents humanity and what any human would do in his situation. People say "I'll beat the hell out of those monsters or this ain't nothin'" and all things high and mighty when in the end, it'll be just as Raki said, "I'm all talk and no action." That's just the way it is. Look back on all the things Raki did and ask yourself, "If he didn't do this..." I'll give you mine, "Without Raki, the protagonist Clare, would've died in episode 4, then where's the story we all know and love?

Think about it:
Clare would never be a claymore would never have known or saved Raki, Clare would be no more children, an adult would be, the creature awakened strongest of all, Priscilla, would never have existed, and because of this:
Alicia and Beth would probably not be claymores, it would not be numbers 1 and 2;
Riful and Dauf would not have been killed by Priscilla;
Clare not be claymore;
Raki would not be saved;
Jean would not have died by Clare;
Ophelia never died;
Sophia and Noel would be alive;
Irene would not have lost his left arm;

Well, then, imagine no Claymore Teresa's death? For more sad and unfortunate bothering that has been Teresa's death, this death was above all necessary.
REMEMBER: I AM NOT SUPPORTING PRISCILLA,THERE IS NOT ANYONE THAT HATE MORE PRISCILLLA LIKE I!