But the dukes eyes are petty and unworthy jubilation
Tone in my last duchess assignment
The Duke believes his guest sees the former Duchess through the same lens of the Duke himself. Being that they are all on the same page the Duke continues with his monologue. He composes himself again, remembering he is respected royalty and professes to the agent that he could not go stooping to her level in order to explain her wrongdoings. For the Duke it is common knowledge that her behavior was unacceptable and she must reform or be punished. Punishment turns out to be the solution as the Duke goes on to explain the outcome of her misbehaving.
His tone does not become feverish or pity seeking like his prior unintentional confession, but instead it is coldly calm. “ Oh sir, she smiled, no doubt, / Whenever I passed her; but who passed without / Much the same smile? This grew; I gave commands; / Then all smiles stopped together(. ),” (lines 43-46). His tone in this sadistic confession is one of cold pride. It projects his prowess and satisfaction with his authority that enables him to right what is wrong. There is no remorse from the Duke, only portrayal of his own go and a subtle warning to the agent of his soon to be Duchess.