The Technical Stuff
Rotor (mathematics) … A rotor is an object in geometric algebra (or more generally Clifford algebra) that rotates any blade or general multivector about the origin. They are normally motivated by considering an even number of reflections, which generate rotations (see also the Cartan–Dieudonné theorem).
What It Means.
The rotor is a self-winding mechanism in automatic watches uses the wearer’s movement to rotate the rotor to wind the mainspring.
Having adjustable Rotor Geometry means a qualified watchmaker can remove the back of the watch and make adjustments to the rotor geometry. Again, this is a complication that is not strictly necessary but every additional element is a nod to the craftsmanship and skill of the master watchmaker.