Morality, Asceticsim, Compassion

Schopenhauer conceives Morality consisting in Self-denial serving as a cure to human suffering.  Because suffering has two roots, 'self-denial' has two meanings to him.  The two roots are Individuality and Will, so, accordingly, Self-denial can be expressed in two ways--Compassion, in which Individuality is overcome, and Asceticism, in which the Will is suppressed.  Thus, insofar as Kant's Highest Good is of an individual, i. e. the combination of Virtue and Happiness, it fails as a Moral doctrine, from Schopenhauer's perspective.  However, Kant could respond, with Spinoza and Nietzsche, that the source of suffering is weakness, the solution to which is empowerment.  He could then point out that Schopenhauer implicitly agrees with that diagnosis, since Asceticism is an instance of self-empowerment that is inferior to the capacity of Reason.  Still, that response does not account for the 'duty', in Kant's doctrine, to promote the happiness of others, though not that of one's own, which does not necessarily empower others, thus effectively functioning as a duty of Compassion, and, thus, as vulnerable to Schopenhauer's challenge.