@Pocky8 I interpreted the words as telling Leslie that when the time comes when she's getting married in the future, after becoming an adult (the ceremony would happen in a temple), the duchess still wants Leslie to be her daughter that day.
@AkaiHidan Yeah, obviously nobody but the extremely desperate would send a little kid to a real fight. However, training would be a different thing and should begin as soon as possible. If she's not trained, she should never get anywhere near battles. But that might be a problem if the Salvatore family's only duty in the Empire is to be the elite guardians. It might also go against their sense of duty and honour to keep a considerable asset hidden and inactive just because she's so cute.
@MeiraEve Yeah, that was basic magic control training and extremely useful, but it's not really combat training, though also necessary for it. As I've understood it, the Salvatores are warrior nobles.