"You're looking quite wizened today," is a something you should never, ever say to your grandmother, no matter how shriveled with age she might be. Think of a caricature of a witch — not your beloved granny.
The verb wizen has fallen out of usage, but the past participle, wizened, continues to function as an adjective meaning wrinkled and shrunken with age or disease. You will see lots of elderly, wizened faces at the park feeding the birds and watching the children play. Although you might expect that folks with lined faces have learned a thing or two, there is no etymological connection between wizened and wise.