@M_Nagaiisawa
"Ozeu-sama" is an Edo-era colloquial spelling of "Ojou-sama", not a misspelling. It reads oddly to us, but it's more humorously old-fashioned than incorrect. (It would be akin to adding extra letters in the style of what was used before English spelling became more standardized, so you'd get something like "Millaydie" or "Miladie", but it's generally been accepted in translation as not demonstrably different from the usual.)

That's right, the sound changes from classical Japanese would often be done automatically in a speaker's head, too - Ozeu>Ozou>Ojou. In this way, it can be seen as a variant spelling with the same pronunciation, something which is very rare in Japanese, only occurring in cases such as this; you see it sometimes in Kancolle works, such as Houseou instead of Houshou of Yufudachi instead or Yuudachi. There were lots of changes from Classical to Modern Japanese, but most of the weirdness disappeared, leaving only a few holdovers - most notably the -zu negative.