This second stanza is perhaps one of the most most disturbing images in Yeats' poem due to its multilayer impact and meaning.
The key to these two lines lies in the poet's use of adjectives in parallel structures. Here, there are three adjectives referencing Leda ("terrified vague", "loosening") and only one referencing the swan ("feathered"). Along with another case of bodily fragmentation that dehumanizes Leda and another reference to her bewilderment, the overall intent of this line is identify Leda as not only a simple victim, but a powerless and, indeed, a complying one (where by her own volition or not). Although Leda is "terrified" in her situation and a general theme of struggle is maintained throughout the poem, her fingers are "vague" in their defense of her body. Her "loosening thighs" tell of acceptance, as if she is unsure of her true affections toward this swan, or is being brainwashed or hypnotized during the act. These images stand against one another, however, and it is difficult to state with any certainty if these lines are meant to depict rape or mere seduction, and to what degree we are to believe this in either case.
In the case of the swan, the noun following the adjective, "glory," is especially telling. Where Leda is terrified, the swan's body is described as "The feathered glory", as if Yeats admires his beauty. If the poet admires the swan's beauty (an aspect of Leda notably missing), he may also condone this act; the question posed here connotes an air of incredulity at Leda's attempt at defending her honor, perhaps posed by a third party allied with Zeus (see Analysis: Point of View). It is important to recognize that this third person may or may not be Yeats himself.