The paper was only on the status of women in the Celtic world from the Halstatt period to the Norman invasion. Thats true, but as with all written sources on "barbarian" cultures you need to offset information with archaeology to get a more complete picture. For example no classical author that I know of mentions female warriors in continental Celtic society (some describe how intimidating they are or how when the Cimbri and Teutons were retreating the women took up weapons to slay the deserters and persuing Romans, but these were not warriors as such) but the archaeological data does show some women were active in battle, but again as you point out these were in the minority.
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