In FTB Unleashed (1.1.4), it shows Soul Shards existing. But I can't seem to find Vile Sword. This a bug anyone else stumble upon?
Vile Swords, Vile Powder, and the Soul Forge are all removed in the newer version of Soul Shards. If you want the Soul Stealer enchant, I've heard that it's now just a normal enchant for any weapon, but I can't confirm ever seeing it pop up. Alternatively, you can use the Force Infuser from Dartcraft to add Soul Stealing to a weapon.