From Wikimedia; image made even lighter by gogm.
Alathea Talbot is wearing over-sleeves of some description, probably hanging sleeves.
Keywords: 1620, Rubens, Alathea Howard, Alethea Howard, Alathea Talbot, Alethea Talbot, Countess of Arundel, Talbot family, Howard family, Countess, British, bertha, lace, tabbed sleeves, hanging sleeves, long full false sleeves, cuffs, ruffles, draped jeweled bodice ornament, bracelets