Is the concept of "Female Warrior" such as "Skjaldmær" or "Amazon" Historically accurate or are they a work of fiction?

There are some aspects of gender theory here that I do not feel myself equipped to talk about aside from being up the problematizing example of the Albanian sworn virgins (burrnesha), who are born as women but reject that gender designation to take on a masculine social role. Archaeologically, they would present the same way as "shield maiden" burials do--as a woman with traditionally masculine weapons. But it is not really accurate to call them "warrior women"--they do not consider themselves women and others don't consider them women either (this article has a number of first person accounts that illustrates what I mean here). This is absolutely not to say that when a female skeleton is buried with weapons we should interpret them as being like "sword virgins" or even consider that likely, but just to bear in mind that there is a whole range of social possibility that needs to be considered when interpreting these matters, and often they do not show up in dusty bones.

Now, from a very narrow sense of "are there historical warrior women" the answer is a very clear yes. One example on my mind now is from southwest China during the late Ming, in which quite a few military leaders were women and women fought in the ranks during the brutal civil wars that engulfed the region. A notable example is Qin Liangyu (discussed in this thread), one of the most effective Ming generals of the period who was personally decorated by the emperor. And there were others as well, such as Dong Qiongying, the wife of Ming general Zeng Ying, who led his soldiers after his death. In both cases their official position was due to marriage, but particularly in Qin's case they maintained personal loyalty and were leaders in their own right.

There are also women recorded as fighting in the rank and file, particularly among the "indigenous" people of the region, and this is where a somewhat tricky issue is raised: frequently, women warriors are attributed to "barbarians", which we can define as James C Scott in The Art of Not Being Governed as those people who are not brought under the administrative ambit of a state (it is a bit more complicated than that, but that will do as a quick sketch). Or in other words, the barbarian is the "other" society, and thus is projected onto them all manner of strange inversions. One inversion being gender, and thus you have the Greeks attributing to the "Amazons" a society in which women war and men weave. This is not to say we can therefore reject out of hand any accounts of warrior women as mere literary device, but rather there are two sides here one one hand, there are in fact "other" societies, a whole of different social norms and configurations, and we cannot expect that the features of one are universally prevailing. But also there is powerful reason for people to project "otherness" onto outside societies, and so we cannot always take ethnography at face value.

Information on SW China comes from Kenneth Swope's On the Trail of the Yellow Tiger: War, Trauma, and Social Dislocation in Southwest China During the Ming-Qing Transition.