"おぜう" seems to be a nickname for Remilia but I'm not familiar with it and I've no idea what to translate it into.

Any help there would be appreciated.

Rampardos said:
"おぜう" seems to be a nickname for Remilia but I'm not familiar with it and I've no idea what to translate it into.

Any help there would be appreciated.

That's most likely from the usual "Ojou-sama" or "Milady" that Sakuya says, except it's abbreviated and slurred I guess.

"Ozeu" is an Edo-era colloquial spelling of "Ojou", apparently. According to the Nicopedia article on the term, it's used as a nickname for Remilia specifically when she suffers a charisma break/loss, though I can't say she looks that way here.