It is not clear why the sight of Samuel causes the woman to recognise that her client is Saul. Her client had already told her that he was looking for Samuel. Perhaps as the spirit appeared, she may have heard it call Saul by name.1 Alternatively, if the spirits normally spoke without any visual appearance, the appearance of Samuel makes her realise that her client is especially important and therefore must be Saul.2
12 Lorsque la femme vit Samuel, elle poussa un grand cri, et elle dit à Saül: Pourquoi m'as-tu trompée? Tu es Saül!