Only piece that adds Dark magic skill for BLM's in the feet slot other than Inferno sabots which is only triggered by new moon.
However due to the difficult nature to obtain the Harajnite shell used for crafting these boots, they remain in the dark for the effort/reward is minimal and only obtained for perfecting a BLM...
lol@Axle. The reason "nobody wants them" as you say is because the shell was really hard to get so nobody ever made them. As a BLM myself I would love these feet.