Which poetic technique does shapiro use in this line? (the nervous blue flash in his eyes)
answers -
imagery
irony
simile
enjambment

The poetic technique that Shapiro use in the line

“the nervous blue flash in his eyes” is:

imagery  

Imagery is a vivid language that appeals to the senses. Imagery is a literary device which includes languages which are descriptive. It functions as a way for the readers to imagine the world of literature in a better way. It also adds symbolism in the piece of art. Imagery is drawn upon the five senses which consist of taste, smell, touch, sight, and sound. It helps in better imaginings of the artist's world in his work.

often a noun phrase is just a noun or a pronoun:

people like to have money.

i am tired.

it is getting late.

because he was killed by the black arrow.