Arabella warned Eloisa so that the latter would not be careless with the book.
After all, since it was a language used for casting some magic spells, people might kill just to get their hands on it. Thus, such a safety measure was necessary.
Arabella already knew though that Eloisa would treasure it since she had been looking for such a book for a while but could not find one.
"My deepest gratitude for this book, Your Imperial Majesty," Eloisa thanked Ferdinand and glanced at Arabella with a knowing look and smiled.
[Elder sister must have told him. The gifts for Elder Brother Benjamin and Nicholas both suited them well. His Majesty would not have known without Sister's help.]
Eloisa knew Arabella was the one who told Ferdinand about this so he knew what gift to pick.
Arabella simply smiled back, glad that what she recalled her siblings liked was still the same in this life.
