In «كثير الرماد», the principal implied target is the quality of generosity. In «الكرم تحت ردائه», generosity is explicitly mentioned, then attached to the wearer through the image of what lies beneath his cloak: the target is the attribution of generosity.
To classify an instance, ask what *new* meaning the indirect route supplies. Merely finding an adjective or pronoun in the sentence does not by itself determine the category.