“Wan” (pálido, tenue) is an adjective and it can refer to your complexión or face or your general feeling.
How art thou today? “I am feeling a little wan” (me siento un poco pálido o indispuesto). Click here to read the article “how art thou”?
Sometimes mortals might smile at you and give you a “wan smile” (lánguida), meaning that it is probably not a genuine smile, perhaps “half-hearted” (de conejo).