The imagery of Aunt Jennifer sewing the tigers expresses the view that the society that Adrienne Rich was living in relegated certain genders to specific roles. The stationary Aunt Jennifer plays into the sexist trope that women are best suited for passive pursuits like knitting or sewing.
The imagery of the stilled aunt is juxtaposed with the imagery of the active tigers. The contrast between the two images arguably expresses the view that women have the ability to create forceful, autonomous entities, but society does not confer upon them the ability to be confident or fearless.
It’s as if the aunt’s creation of the tiger embroidery is a metaphor for childbirth and its fraught position in Rich’s society. A woman can give birth to a boy who can grow into a man as powerful as a tiger—one that’s undaunted by other men. Yet a woman herself should not expect to be treated as powerful; she should yield to men.
The wedding band on Aunt Jennifer’s hand is a key image and metaphor that reinforces the submissive role of women in Rich’s society. The speaker describes the wedding band as a “massive weight.” This suggests that the wedding band is a metaphor for oppression. It's reasonable to claim that the band represents an unfavorable view of marriage. Here, marriage is not a loving, equitable union between two people, but a burdensome, suffocating punishment for women.