A euphemism for her murder. Shows the power he has - can just kill her without consequence, but also shows such an overreaction - murder is a sign of lack of control
He won't lower himself to talk to his wife and confront her about what he fears, as it would show him as paranoid and weak. Suggests there's no point arguing with a woman as she is so far below him, and incapable of rational thinking
He places a lot of value in a statue "thought a rarity", clearly believing his status and wealth should be seen as more valuable than anything available to the common man
Is ominous as it suggests the Duke viewing the subject of his dead wife as a piece of art rather than sentimentally as his wife, immediately suggesting she was only ever a possession to him
Ferrara: '"That's my last Duchess painted on the wall, Looking as if she were alive. I call That piece a wonder, now: Frà Pandolf's hands Worked busily a day, and there she stands."'
The line "I call that piece a wonder" is ominous as it suggests the Duke viewing the subject of his dead wife as a piece of art rather than sentimentally as his wife
The language used is simple, which works to make it seem like a normal conversation and draws more emphasis to the places where literary devices are used