"!! "
what is meant by an artist personal style and what role does it play on the historians efforts to identify artworks as representative of art movements?

An artist’s personal style just means it is an artist’s way of using the art elements and principles to reproduce what they see and to express their idea and feelings

In the visual arts, style is a "...distinctive manner which permits the grouping of works into related categories". or "...any distinctive, and therefore recognizable, way in which an act is performed or an artifact made or ought to be performed and made".