his countenance bespoke bitter anguish, combined with disdain and malignity
The nouns here are all associated with Satan and the Satanic in Paradise Lost: e.g. "anguish" (II.568; VI.340); "disdain" (I.98; II.680; V.666); "malign" (III.553; IV.503; VII.189). And yet, the framing language forces us to consider perspective: "bespoke" is not the same as "constitutes" in its implicit representation of reality; and if Victor, even as he articulates it, openly remarks that he "scarcely observed this," where, then, might his terms come from? As we will learn from the Creature himself (II:7:7), it is easy to insert oneself (or others) into the mythic texture of Paradise Lost: thus it might appear, as it were, that Victor does so first, here defining the Creature as Satanic not from sharp empirical observation but from literary—that is to say, cultural—convention.