What are some rhetorical devices in Macbeth, Act 1 scene 7?

A rhetorical device is a persuasive device. In Act I, scene 7, Macbeth has had second thoughts about murdering Duncan, and tells Lady Macbeth he can't go through with it. Macbeth remembers that he owes such a good ruler (or any ruler) his loyalty and, further, that as his guest, Duncan has earned extra protection from Macbeth, not murder and betrayal. Finally, Macbeth remembers that he just been honored by the king and wants to enjoy the good feelings and well wishes of other people ("golden opinions ... in their newest gloss"), not immediately mar the moment with murder. He wants to be toasted and celebrated and complimented and to enjoy his moment in the sun as one of Duncan's favored men. He only tells Lady Macbeth the last reason, but we, the audience, know the other two have gone through his mind. Lady Macbeth has to muster all her rhetorical (persuasive) powers to motivate Macbeth to carry through with his bloody plans.

She does this in several ways. First, she attacks his manhood (an ad hominem or "attack the person" argument) and questions his love for her, saying that if he can promise he will do something and then not act on it, how can she be sure of anything that he says or even that he loves her? She attacks him for not taking what he wants, asking him if he is afraid to act on his desires, another attack on his manhood.

Second, she sets up an either/or argument, telling him he either needs to take what he wants or he is a coward. This is a type of rhetoric that allows for no gray areas or middle ground: either Macbeth kills Duncan or he is a coward, unmanned in her eyes and his own. Macbeth could argue back that it could be considered courageous not to murder one's king, but he doesn't, and Lady Macbeth doesn't give him a chance to think as she rushes on.

She continues to persuade, rising to a cresecendo by using the rhetorical device of emotional appeal, telling him that she would dash out the brains of a "gumless" baby suckling at her breast if she had promised to do so. 

Finally, she reassures him that as long as he screws up his courage and does what needs to be done, they can't fail: they have a foolproof plan in pinning the murder on the drunken servants. 

Lady Macbeth's rhetoric works and Macbeth does the bloody deed.