Vexillum percnodictya is a species of sea snail, a marine gastropod mollusk, in the family Costellariidae, the ribbed miters.
The length of the shell attains 21.5 mm, its diameter 4 mm.
(Original description) The narrow, dusky-brown shell is fusiform and turreted. It is many ribbed with smooth ribs. The interstices are deeply cancellated. The columella is three-plaited.
This marine species occurs off Madagascar, Andaman Islands and Australia.