You don't find this to be bias confirmation? What we have is a female skeleton buried with a couple of horses, some weaponry, and some games. That's it. They use this to declare the individual a warrior. It's possible, but it's also complete speculation. Most peculiar, to me, is that that paper and the wiki entry [1] make no mention of the outfit that the skeleton was wearing. It was surrounded by weapons, not equipped with such. Speculating in another direction, did Vikings hold funery rights for those whose corpses could not be recovered? That would likely be a semi-regular event be it from falling on campaign, in battle, or even just being lost at sea. For individuals of high rank, which this grave obviously indicates, human sacrifice was on occasion part of funery rights.

So for instance one of the first things I'd be curious about is the skeleton's diet. This sounds incredible, but there's actually precedent for this [2]. In that study they were able to relatively compare diets noting similarities between the common class, contrasted against the elite class. If I'm going to go against Occam's Razor (and the lack of any meaningful evidence for female viking warriors makes this paper's assumption very much this) I'm going to try to disprove my hypothesis in every practical way. Why was none of this done to at least ensure the person was not a beloved slave/lover/wife of some sort? It seems the only examining the authors of that paper took out was to determine if there was indication of trauma or damage of the skeleton, as might be evidence of battle. They found that the skeleton had not been damaged in battle.

Finally, let me conclude with a little quote from that paper: "Do weapons necessarily determine a warrior? The interpretation of grave goods is not straight forward, but it must be stressed that the interpretation should be made in a similar manner regardless of the biological sex of the interred individual." I think this is illogical. The entire goal of science is to formulate the most probable hypothesis with consideration to all evidence available. The fact that this corpse is a female radically changes the probabilities. If you find the corpse you somehow know to be a well nourished Nazi inside a holocaust mass grave, would you assume he was there for different reasons than the other corpses around him? Obviously. Your interpretation can and should change with every bit of data you discover.

[1] - https://en.wikipedia.org/wiki/Birka_female_Viking_warrior

[2] - https://www.sciencedirect.com/science/article/pii/S030544031...