I think it's the way it's translated. We call it diadeem, but if I look in english for diadem I see princess-like hairbands.
Well... personally I'd simply call it a headband. The definition of a diadem may be broad enough to include it, but it's a pretty obscure and uncommon word haha.
I have only heard it in two places - in a video game, and in here!
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