Gargantua, the giant, is said to have used this stone to sharpen his scythe, which he then took to finish off the soldiers of Caesar
See – The Life of Gargantua and of Pantagruel (in French, La vie de Gargantua et de Pantagruel) a connected series of five novels written in the 16th century.
en.wikipedia.org/wiki/Gargantua_and_Pantagruel