I agree with your first paragraph but not completely with your second. Power is a relation and therefore necessarily takes an object. Ressentiment, because it is an attempt to reclaim the advantage in power relations, is necessarily directed at an external target. That it usually coincides with shame or self-loathing, doesn’t take away its external intention. Nietzsche only understood the self-loathing dimension, but Scheler understood the broader meaning and social manifestations of ressentiment.