Both Uses of

pious
in
Dr. Jekyll and Mr. Hyde

There were several books on a shelf; one lay beside the tea-things open, and Utterson was amazed to find it a copy of a pious work, for which Jekyll had several times expressed a great esteem, annotated, in his own hand, with startling blasphemies.
p. 66.6 *

pious = religious or moral

Had I approached my discovery in a more noble spirit, had I risked the experiment while under the empire of generous or pious aspirations, all must have been otherwise, and from these agonies of death and birth, I had come forth an angel instead of a fiend.
p. 89.1

Definitions:

(1) (pious as in: a good, pious woman)
religious or highly moral
(2) (pious as in: a pious hypocrite)
self-righteous (acting as though one is, or believing one is highly moral when it is not true)
(3) (pious as in: cling to the pious hope)
(describing a hope or wish as) sincere, but highly unlikely
(4) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Much more rarely, piety can refer to devotion or faithfulness as Proust used it in the book, Swann's Way:

"...but when, as had befallen me, such an anguish possesses one's soul before Love has yet entered into one's life, then it must drift, awaiting Love's coming, vague and free, without precise attachment, at the disposal of one sentiment to-day, of another to-morrow, of filial piety or affection for a comrade."