Poem is one-sided. Not only do we not hear from the wife but we do not hear from the envoy. These evokes the Dukes' control and can easily manipulate the story to suit his degree
However the enjambment begs to differ, the unstructured messages being conveyed in different lines undermines the Dukes' ability, he blurts this information in one long frantic stanza
'My' Last Duchess
'my' objectifies his wife, condensing her as his prized possession
highlights his desire for complete dominance in which during the patriarchal society women were seen as possessions to be controlled
COMPARE TO OZYMANDIAS
Both 'Ozymandias' and 'My Last Duchess' present the transience of tyrannical power, ultimately teaching that power is an illusion.