@0luk:
My guess is that in the Japanese version they use the gender neutral pronoun before the masked "knight" reveals herself as a woman.
The Japanese language has such a pronoun that you use in case you do not know which gender the figure / person has when you talk about them.
That way it makes sense in Japanese to be surprised about the "knight" being a woman.
In English however there is no such genderless pronoun to refer to a person.
You are forced to use either the male or the female version in English.
The translator has known that the "knight" is a woman due to reading the complete chapter first.
Therefore the translator used the female pronoun from the start because he/she has known that knight to be a woman from reading the complete chapter.
In the English translation however this then causes the issue about wondering that the "knight" is a woman when she reveals herself.
That is why some translators who have more experience with the Japanese genderless pronoun use a trick by translating the pronoun by using the plural pronouns (they/theirs/them) instead of the singular pronouns (he/his/him or she/her/her).
So the best translation would probably have been refering to the masked "knight" with "they/their/them" until the "knight" takes of the mask and reveals being a woman.
That way the surprise about the "knight" being a woman would have made sense.