I read Being and TIme by Heidegger but some 10 years ago now. I remember this section, because of its somewhat fascist overtones, and had another look at it (out of context) today. Page 386 of that book (the second indexed mention of the term "hero") says:
It is not necessarily that in resoluteness one should explicitly know the origin of the possibilities upon which the resoluteness projects itself. It is rather in dasein's temporality, and there only, that there lies any possibility that the existentiell potentiality-for-Being upon which it projects itself can be gleaned explicitly from the way dasein has been traditionally understood. The resoluteness which comes back to itself and hands itself down, then becomes the repetition of a possibility of existence that has come down to us. Repeating is handing down explicitly - that is to say, going back into the possibilities of the dasein that has-been-there. The authentic repetition of a possibility of existence that has been - the possibility that dasein may choose its hero - is grounded in anticipatory resoluteness; for it is in resoluteness that one first chooses the choice which makes one free for the struggle of loyally following in the footsteps of that which can be repeated.
Is he suggesting that authenticity is an alternative to a genealogy of morals? That instead of asking about the "origin" of a moral belief we can ask whether we ourselves accept it out of ressentiment: or whether we are repeating the work of a "hero" - someone strong who we do not seek to injure?