>of these words: accomplice, exultant, remorseless, sedate, apprehension, ponderous, revulsion.
>
>Sour is the opposite of sweet therefore we are looking for the opposite meaning here. My guess would be revulsion (darkness, evil) as the opposite of Sun (light)

I like your reasoning but I believe Dmitry is right with ponderous and light meant in regards to weight. I didn't think of this myself, but in the definition of the ponderous light is listed as the antonym.