This picture is by artist Robert G Harris, and is one of the most stunning and simply effective covers I've ever seen. There's a shop on the Oregon coast called Robert's Books which has original pulp novel cover art all over the place (usually with a sample of the original book cover to show how it ended up) and I can just wander around looking at those all day long. These days you don't see this caliber of artwork any more, its pretty cookie cutter.
I remember standing in a book store and noticing the same, exact girl was used on like 8 different fantasy novels. Her pose was slightly different, but it was clearly the same girl. In nearly the same pose and setting.