The four swords refer to the four Swords of State. These are part of the Crown Jewels of the United Kingdom, traditionally used during Coronation.

The second part I do not know, and I do not have access to that particular book. Maybe you can post reference number 8, which according to Google Books is mentioned on that sentence. I suspect you are reading that sentence too literally, and in modern English, and in that time it would have meant, "to sit on a chair and be attended to by two of her ladies."

Where did you read it?