Both Uses of

aura
in
City of Bones

Facilis descensus Averno; Noctes atque dies patet atri ianua Ditis; Sed revocare gradum superasque evadere ad auras, Hoc opus, hic labor est. —Virgil, The Aeneid There was a moment of astonished silence before both Clary and Jace began speaking at once.†
Chpt 10

When she let her own eyes fall half-shut, she saw the shimmering aura of glamour that surrounded him, and wondered what they were seeing: Another patient?†
Chpt Epil. *

Definitions:

(1) (aura)
a distinctive but intangible quality surrounding a person or thing

or:

paranormal: a radiant light surrounding a person that is said to be seen by those sensitive to another's life force; or drawn around the head of a saint
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

In medicine, an "aura" can reference a sensation (as of a cold breeze or bright light) that precedes the onset of certain disorders such as a migraine attack or epileptic seizure.