Everybody acknowledges the importance of metacognitive skills and mathetic3 competencies for nowadays learners. Self assessment is only an aspect of them and Confidence Degrees are only one way among others to address the issue. We hope that the first part of this article has demonstrated that some restrictions that are legitimately associated with this technique are carefully taken into account, that there are valid and reliable ways to use Confidence Degrees, and that the second part of the article has demonstrated that this technique offers the potential for new and fecund approaches to old problems. We have decided not to enter the debate of the definition of competency, since place was lacking here and we wanted to focus on technical aspects. Nevertheless, we are confident that this approach can bring its special light in the old debate so well stated by T. S. Eliott : “Where is information we lost in data ? Where is knowledge we lost in information ? Where is wiseness we lost in knowledge ?"