I'm gonna have to disagree. You only need to see the Priscilla example to disprove your assesment. Also, with the "gradual loss" you speak of, the Claymores have time to notice how they are changing and send in their Black Card. I think Claymores run the risk of Awakening if they suddenly and unexpectedly go beyond their limits.

We've only witnessed one example of a Claymore fully Awakening, and that example was of an inexperienced Claymore.

Sure, will power has something to do with it, but I don't agree with your reasons behind it.