Our vintage stationery pen nibs are meant to be used as inserts into older pen shafts. Most of these are for writing - love letters, testimonials, official documents, etc.
They are not calligraphy nibs per se - however a master calligrapher may enjoy some of them for special flourishes and the like.
Because of the their aged patina, they will also combine nicely in niches of altered books (consider the authors writing by candlelight!) or in assemblages, or in a small pin dish on your desk - for inspiration.