She has only a nodding/slight/superficial 'acquaintance with' the facts of the case. [=she knows only a little about the facts of the case]
He seemed cold 'on/at first acquaintance' [=when I first met him], but later I realized that he was just shy.
I only have a 'nodding acquaintance' with Greek history. [=I know only a little about Greek history]
(..) It was placed there this past summer. And she never suspected it was a fake. The replica is very convincing. Only a goblin would recognize that this is the true Sword of Gryffindor. Who is the acquaintance? A Hogwarts Professor. As I understand that he's now Headmaster. Snape. He put a fake sword (..)2011 Harry Potter and the Deathly Hallows: Part 2