Love, that doth reign and live within my thought
It's hard to pick one word that embodies the sonnet since all three sonnets had two main movements.
But since I have to chose one, it would have to be 'fought.'
There are clear images of conflict in the sonnet, from "my captive breast" to "his banner rest." Love reigns on one side and Love also takes a cowardly flight on the other. We have lords and ladies and purposes and death. The conflicts in this sonnet also seems to be tiered.
First, the poet fights with love, and the end result is that Love reigns in his captive breast. The struggle takes more than a third of the sonnet, perhaps to show that the personal struggle with Love is the most important and hardest. "Clad in arms wherein with me he fought." One sense of the arms can be the physical image of cupping your hands over the heart as it beats wildly for love. Or in wrapping your arms around yourself to console as your love causes you anguish. The emotion that Love brings fights with your will to compose yourself.
The arms are more likely to mean weapons in the historical context. Before the fight was only in a emotional, abstract level, now it means war. The fight is between an armed warrior and a captive, it's no wonder the end result has "Oft in my face he doth his banner rest."
The sonnet starts within his mind, "Love that live within my thought," and now it moves to the unattainable woman, "she that taught me love and suffer pain." There is a conflict between the hope and desire, the love and the pain that she causes. "My doubtful hope, and also my hot desire" could refer to the poet's hope, the poet's desire, or the lady herself as the personification of the hope and desire. Either way, the conflict is now separate from self and becomes the lady's reluctance to be in love. When "Her smiling grace" "look to shadow and refrain," the poet's love causes anger. The ambiguity leaves open to suggestion whether it is her smile that turns to anger, or her modest smile that turns the poet's love to anger. It doesn't seem to matter which field the poet fights with Love; he always loses.
The last stanzas with the lord is a bit confusing. The poet refrains himself because of his lord, but somehow he's stepping on him? "Yet from my lord shall not my foot remove"...so in the end, the poet resigns himself to get killed by the lord for pursuing his love? Or he suicides because he can't take the love. He embraces death in the last fight with love and dies, or feels like as he is dead.