Macbeth is indeed killed by someone "not of woman born"-apparently, Macudff was delivered in a Caesarian section and so, in an era when this medical procedure was uncommon, seems not to be "born" in the usual biological way. Macbeth is also killed when Birnam wood comes to Dunsinane, since the soldiers attacking Dunsinane camouflage themselves with tree boughs that make it look like Birnam wood is approaching.
I would say the first sentence is grammatically correct
Hello. You did not say which poem this question refers to, which makes it impossible for me to give you an exact answer. However, I will try to help you by showing you what the tone of a poem is and how those words can change it. I hope it helped you.
The tone of a poem is the feeling that the poem gives to the reader while reading. A poem with melancholy and painful words has a sad tone, a poem that presents nature as something inspiring, has a reflective tone, for example.
The words shown by you, in the question above, refer to something difficult to be perceived and visualized, requiring a certain effort. With that we can project that these words modify the tone of the poem presenting a tone of search, of difficulty and effort.
Thank you for answering your own question.