Kromlech or Vahn can stand there and pelt her with arrows. Doesn't do much damage, but it adds up. SImply shoot two or three arrows (I could get off three with Vahn), then quickly switch over to your melee weapon/shield stance, and block the flying swords. This ev en works after her second electric "growth", when the dwords rain from the sky. They're STILL BLOCKABLE!
I just beat her on Extreme with Adrianna, doing the same thing, but it's a bit easier with her. Just use Melf's Acid Arrow. You can easily get 3-4 shots of it in, and then block. And since you don't ever have to switch stances, it's even easier.
If you block too many times without retaliating, Eldrith is gonna run up on you to deal some melee damage. Heed Kaledon's words, and stay out of her reach! Just run away until she goes back to chucking her sword at ya.
If anyone else wants any boss straegies, lemme know. I know the tricks for all of em with Vahn or Adrianna, and I'm currently going through Extreme with Kromlech. The game doesn't have THAT much replay value (I really wanna get the second one, but I'm broke), but I like it! ;-) --- Just because you're paranoid.. doesn't mean they're not out to get you...