We'll know more about the bracelet soon.
As for the Salvatore, all of them were against her going, but let her go since it was a precious memory for Leslie. If I remember right, all of her family was busy that day one way or another, that's why none of them accompanied her during the trip. Even so, they prepared many of their knights and also asked Konrad so that she would have enough protection. They probably didn't expect her to purposely go and let herself be left alone or get upset with the knights.
The knights are servants of her family, so it's not like they can go against her and her orders.
If people want to blame anyone, it should be Leslie for her actions, and even so she shouldn't be because she thought it was a person she could trust and was grateful to.