Final answer:
The phrase 'geniality personified' is the opposite of 'atrociously' and clarifies its meaning by contrast.
Step-by-step explanation:
The phrase that clarifies the meaning of "atrociously" by providing its opposite from the given excerpts is "geniality personified". The word atrociously suggests something that is horrifyingly wicked or of very poor quality. In contrast, "geniality personified" suggests a welcoming, pleasant, and friendly demeanor - essentially the opposite of something that could be described as atrocious. Thus, it offers a clear antonym to the term atrociously, thereby helping to clarify its meaning through juxtaposition.