Both Uses

luminous
in
Washington Square, by Henry James
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To her mind there was nothing of the infinite about Mrs. Penniman; Catherine saw her all at once, as it were, and was not dazzled by the apparition; whereas her father's great faculties seemed, as they stretched away, to lose themselves in a sort of luminous vagueness, which indicated, not that they stopped, but that Catherine's own mind ceased to follow them.†
Chpt 2
Catherine could think of nothing of the kind, and Morris's luminosity seemed almost pitiless.†
Chpt 20 *

Definitions:

(1) (luminous)
glowing or shining

(also used metaphorically to describe beauty or intelligence)
(2) (meaning too rare to warrant focus)
Much more rarely, luminous can mean beautiful, inspiring, or beautifully clear and understandable.