Duke Sanchez: "I suppose I can take that as confirmation... That my daughter married the only member of the Imperial Family that can't keep his mouth shut?"
Edward: flinches
"Even if they cannot claim her power for themselves, they stand to benefit just by denying it to us."
Oddly enough, no, they actually don't. The Empire doesn't need Carolina to be the biggest and most powerful country in the setting, and there's no way that the Empire doesn't regard the loss of a member of the Imperial Family as a cassus belli.
Now, if they had an equal-ish rival who actually would benefit from humbling the Empire, and was in a strong enough position that the Malcosians couldn't just raze their country to the ground in response...
"Unthinkable. You'd do well to learn a thing or two from Lady Flora."
Calm down, Mrs Danvers! You're not supposed to go off the deep end until after Flora dies!
"I need but will it, and the faithful shall rise across the continent, and in our name, wage a holy war."
Of all the harebrained schemes...
European history says Flora's got a better grip on how well that will work than Archbishop Mills does. Not just because he's not the head of the church (yet), but because actual Popes routinely lost when it came to open confrontation with European Royalty. The only times they didn't were when they could ally with one King against another. And Malcosias doesn't have a rival strong enough for Mills to hide behind...
Mills: "So much as twitch in the direction of betrayal, and... er... kinda lost my train of thought there." Looks away awkwardly.