Horsemen and chariots have a long tradition in Greek funerary iconography. In this very late manifestation, the rapidity but surety of execution heightens the question of whether the scene is to be understood literally or whether the horseman is a representation of the deceased.
Oakley, John H. 2004. Picturing Death in Classical Athens: The Evidence of the White Lekythoi. p. 186, Cambridge: Cambridge University Press.