The study of the history of words and their meanings
Hello there!
The details from the narration relate Rainsford’s impression of Zaroff are
*almost bizarre quality about the general's face
*his thick eyebrows and pointed military mustache were as black as the night
*His eyes, too, were black and very bright
*the face of an aristocrat
Those are descriptive details that allow us to know how is the reaction and impression of Rainsford.
Hope this helps.