This is a fairly recent book, having had my hands on it sometime between 1996-1998. It was definitely a picture book. I can’t remember if the classroom copy was paperback or hardcover, but I don’t think the book was published any time before 1985 and it was more likely to have been put out after 1992.
My clearest memory is of a page showing a slim girl with cropped black hair who, as a thief, had a magical belt or girdle that made her invisible. The belt may have been silver. The story took place in an imaginary land or in the past; I think she was dressed in a very sort of medieval page way.
I am certain there were other girls with other specific talents and magical objects in the book, but I am unsure as to how many. Judging from trends in children’s literature it was probably 3 or 7.
Thank you so much!