Vorpal is added by redpower 2 - it is an enchant that has up to 4 levels and gives you a chance to "execute" your target, dealing very high damage and increased chance of dropping a mob head.
Disjunction is also added by redpower 2 afaik - it has up to 5 levels, and does increased damage to endermen. It cannot be stacked with sharpness or any other mob specific damage increase enchant
Soulstealer added by SoulShards mod - increases the amount of souls you get per kill by 1 per rank, maximum rank 5. You have to put it on a vile sword to begin with but can be transfered using an uncrafting table.
Fiery Aura added by Twilight Forest mod - an enchant that only appears to be on fiery armor, which is made from fiery ingots, which in turn is made form fiery blood (I think al lthose names are correct?). This is a drop from a hydra in the twilight forest. The enchant has up to 2 ranks and deals fire damage - it supposedly does it to things around you but i think it's only to things that hit you.