姿色 refers specifically to a woman's physical attractiveness, often with a slightly evaluative or even commodifying tone. It appears in phrases like 有几分姿色 ('has a certain degree of good looks') or 姿色出众 ('outstanding beauty'). Unlike the more neutral 漂亮 or 好看, 姿色 emphasizes looks as a trait that can be assessed or compared, and it's rarely used for men.