In this early moment of the poem, the speaker has lost her grip—for reals. She cannot "catch" Ariel's neck. She has nothing to hold on to. She is completely powerless.
Hauls me through air— (15-16)
Again, we see the speaker in a position of powerlessness. She is "haul[ed]" through air by Ariel. She is the object, not the subject, in this stanza. She has no control, and thus, no power.
Godiva, I unpeel— Dead hands, dead stringencies.
And now I Foam to wheat, a glitter of seas. (20-23)
The speaker's transformation to a position of power happens in these lines. She "unpeel[s]" the things that are holding her back in life. She compares herself to the powerful sea, which overwhelms the wheat of the fields that she's passing on her wild ride. Note that her ascension to power is all in her head; nothing changes physically. It's all mental.
And I Am the arrow,
The dew that flies Suicidal, at one with the drive Into the red
Eye, the cauldron of morning. (26-31)
The speaker is ultimately able to gain power by submitting to the drive, to the will of Ariel. In giving up her attempts to control her situation, the speaker is set free. Her drive into the sun is couched in morbid language—it's "suicidal"—but the suicide here is the death of her former self. This "suicide" gives her the power to be united with nature, to harness Ariel's awesome power.