Dune Is Almost Entirely Faithful to the Books — Here Are the 9 Key Differences

When the Atreides first arrive on the Arrakis, Lady Jessica decides on Shadout Mapes to be her servant, who presents her with the fabled crysknife of Arrakis. The highly sought-after blade is made from a tooth of Shai-Hulud — or the sandworms — and must not be sheathed unblooded, as per the rituals. In the book, Jessica draws a minor scratch on Mape's chest before sheathing the blade to keep up with the convention. This tidbit is missing in the movie.