“High-souled,” used here to describe Grace Crawley, is a literal rendering in English of the Latin parts of the word “magnanimous.” In English this word now means “generous.” Trollope here recalls the Classical (and archaic English) use of the word to mean “brave” or “courageous.” [EB 2006]
Aegis of first-rate county respectability
The aegis is a shield, or sometimes a type of garment, wielded by Zeus and often used by Athena. The term has been borrowed into English to refer to a shield in a more figurative sense. This is seen in the narrator’s description of Mrs. Robarts and Lady Lufton’s kindness to Grace Crawley. Using the word “aegis” elevates the power of their aid. [EB 2006]
Sources: Cassell’s Dictionary of Classical Mythology.