Will to Power and Etiology of Nihilism

The Genealogy of Morals implicitly outlines an etiology of Nihilism: 1. The internalization of the Will to Power qua principle of Aggression: 2. The infection of that introversion by the negativity of Ressentiment; and 3. The resultant formation of a Will to Nothingness.  However, that analysis is preceded by a more fundamental corruption in Nietzsche's doctrine--when what begins as a principle of Empowerment, i. e. the characterization of the Will to Power as a "bestowing virtue", in Zarathustra, degenerates into a principle of Aggression in Beyond Good and Evil, and continuing into the Genealogy.  Taking that origin into account, Nihilism can thus be diagnosed as a corruption of a process of Self-Enhancement into one of Self-Destructiveness.  So, the attendant hermeneutical question is whether or not Nietzsche's post-Zarathustra oeuvre itself exemplifies a succumbing to Nihilism, and, if #258 of BGE is any indication, it does.  For, there, as has been previously discussed, he characterizes as "healthy" a process that, upon closer examination, is revealed as self-defeating.