The bad news first: while many women have been found buried with weapons, the evidence doesn't support the claim made in the title of equal gender representation on the battlefield. The 2011 study that the article cites concludes: 'Although the results presented here cannot be used to determine the number of female settlers, they do suggest that the ratio of females to males may have been somewhere between a third to roughly equal.' The key thing to note is the word 'settlers': the article is arguing that women migrated from Scandinavia to England with the invading Viking army in the 9th century. Several of these women, the article notes, were buried with weapons, but they are still far outnumbered by the armed men. Most of the women settlers mentioned in the study were buried with 'traditional' female outfits: brooches that held up their aprons.
The good news, though: while women buried with weapons are rare, they *are* being found, and this is in large part thanks to an increased willingness to trust the bone specialists. Archaeologists have been using bones to identify the biological sex of skeletons for the past century, but when burials were found which didn't fit their notions of 'normal,' they tended to assume that the bone analysts had made a mistake. This is not entirely unreasonable, because bones are often so badly decomposed that it is impossible to tell the sex of the person. But I can point to cases where the bones clearly belong to a woman, and the archaeologists insisted that it had to be a man because only men were warriors. That's modern sexism plain and simple, and bad archaeology. But thankfully, archaeologists in recent decades have become aware of this problem, and as a result, more and more women are showing up with weapons!