What are the figures of speech used in the poem "Anthem for Doomed Youth" by Wilfred Owen?

There are lots of figures of speech in the second stanza of "Anthem for Doomed Youth," most of which draw on a motif of light and darkness. For example, in the opening line, "What candles may be held to speed them all?", the "candles" are symbolic of remembrance. The rhetorical question implies that these soldiers will not be remembered adequately for their sacrifices.
In the next line, the speaker says that "in their eyes / Shall shine the holy glimmers of good-byes." The light in the eyes of the soldiers here might be symbolic of the hope with which they set out for war. The fact that the light only "glimmers" suggests that it is a weak, faint hope. The adjective "holy" to describe the "glimmers" of light alludes to the purity and innocence of the boys setting out for war.
In the following line, the speaker says that "the pallor of girls' brows shall be their pall." A pall is a piece of cloth draped over a coffin at a funeral. The metaphor describing the "pallor of girls' brows" as the soldiers' pall implies the deaths of the soldiers will be marked by the sickness of the girls they leave behind.
The concluding line of the poem, "And each slow dusk a drawing-down of blinds," uses symbolism and imagery to emphasize the number of deaths consequent of war. The dusk is a time of the day when light is fading to be replaced by darkness. Dusk is thus usually symbolic of death or dying. This image of darkness is then compounded by the image of the "drawing-down of blinds." The impression of darkness alludes to the lives of the soldiers being extinguished. And these deaths are as inevitable as is the setting of the sun.

Some of the figures of speech employed by this poem include simile, personification, and alliteration. In the first line, the speaker asks, "What passing-bells for these who die as cattle?" He compares the young men who die in war to cattle, via simile, in order to emphasize the way they seem to be slaughtered, thoughtlessly, and by the thousands. A simile is a comparison of two unalike things using the word like or as.
In the next few lines, the guns are personified as feeling a "monstrous anger" and the rifles are "stuttering" while they "patter out their hasty orisons"; orisons are prayers, and so these lines personify the rifles by stating that they can pray. Personification is when something nonhuman is granted human characteristics. Later in this stanza, the "wailing shells" are personified as "choirs" that possess a "voice of mourning."
Alliteration is the repetition of the initial consonant sound in words, and it is often used to mimic or enhance the words' actual meaning. In the third line, the phrase "rifles' rapid rattle" is an example of alliteration. We can read the repeated "r" sound as echoing the sound guns make when fired over and over.