This quest is really starting to annoy me lol, i found a good way to take health off one though. put it in a pitfall trap, use the paralyzing knifes and it goes into a 'sleep effect' attack them while there in this and it deals quite a good amount of damage. btw apperently its better to take out silver soul first as he has low health and his air attack is annoying, really annoying. deals loadsa damage, poisons you, sends you into stars.