What literary device is most clearly used in this passage.

no! i am not prince hamlet, nor was meant to be;
am an attendant lord, one that will do

I believe that the best answer for this question is an allusion. An allusion is a literary device where a writer refers to some other work of literature in their own work of literature in order to make some point or add emphasis. Here, T.S. Eliot is referring to Hamlet by Shakespeare. The speaker is asserting that he is not indecisive, as Hamlet is. Rather, he is like Polonius, a servant of the king in Hamlet. Polonius is a very cautious character but is overall fairly useless. I hope this helps.