It is supposedly possible to get very high enchants using FTB mechanics that would otherwise not be possible. There is one guy on our server claiming to have a diamond sword with "Vorpal IV, Sharpness V, Knockback II, Unbreaking III, Fire Aspect II, Looting III". If that's true (and I believe it so - no creative enchanting) there must be some combination of book usage, anvil usage a recrafting using uncrafting table that allows this. But all my tries of even getting close to this enchant were in vain so far. I always end up on "too expensive" message from anvil. Anyone knows hot to get to this kind of ridiculous enchant?