Have taught to ignorant men most violent ways, (line 3)
Gonne seems to have a special influence over these men. Part of the explanation is class; she belongs to the intellectual elite, while the "ignorant men" are working class. But gender no doubt plays a role too, as it did with Helen of Troy, "the face that launched a thousand ships."
With beauty like a tightened bow (line 8)
Gonne has a classic beauty, like a figure from a Greek statue or painted on an urn. By comparing her beauty to a weapon, though, Yeats cleverly suggests the tension, maybe even violence, that lies beneath.
Being high and solitary and most stern? (line 10)
OK, this part actually seems to buck the gender trend that runs throughout the rest of the poem. "High," "solitary," and "stern" are adjectives that could apply to either gender. They serve to dignify Gonne, to make her seem like a powerful ruler.