What is it that makes someone a woman, exactly? Stating that our speaker is an outsider allows Sexton to trouble the assumption that "women" are all the same.
A woman like that is misunderstood. (13)
Notice something funny about these lines? Our speaker doesn't say a "woman like me." Nope, it's a woman "like that." It's almost like she's turning the lines before this one into a case study: here's one example of a woman. And here's another. Notice how they all seem to be ostracized? Hmm...
A woman like that is not ashamed to die. (20)
Sexton turns gender into a battleground – one where women are persecuted for…what, exactly? Well, that's part of the power of her statements. Because she never specifies exactly why she's being persecuted, we're left to assume that it's just because she happens to be a woman.
fixed the suppers for the worms and the elves: (11)
Sexton combines the utterly routine with the really, really weird in this line. Fixing supper is a pretty traditionally feminine occupation. Fixing dinner for worms and elves? Well, that's not exactly an everyday occurrence. Could this mean that our speaker is slightly more conventional than she seems to be? Or is she deliberately flouting conventional occupations?
I have ridden in your cart, driver, waved my nude arms at villages going by, (15-16)
"Nude arms" should be sexy, right? Well, not exactly. See, in this line, we get the sense that our speaker been forced to strip (her arms, at least) by the same folks who are planning to burn her at the stake. Forcing her speaker into a display of her body allows Sexton to underscore the ways that gender norms are reinforced by punishing people who dare to break them.