Then Esther the queen, the daughter of Abihail,… wrote. The unusual designation of Esther as "daughter of Abihail" can only be accounted for by her having so designated herself in the letter. With all authority.
Rather, "with all earnestness," or "impressiveness." Literally, the word used means "strength." To confirm this second letter of Purina. The first letter is the one which is mentioned in verses 20 and 26.
That letter having elicited the favourable reply contained in verses 26-28, a "second letter of Purina" was now issued, "confirming" and establishing the observance. It went forth not as an edict, or in the king's name, but as a letter, and in the names of Esther and Mordecai.