Another thread questioned whether the Weakish Undead Powers contained in the latest Sola release was too difficult. I decided to find out using a new game I recently started. My party consists of me (fighter dualled to a mage), Minsc, Jaheira, Aerie, Nalia & Anomen. Please, no comments on the party composition. I just wanted to make clear I wasn't using four Undead Hunters, a High Priest and an Archmage. My party had already finished Chateau Irenicus, solved the Circus Tent mystery, freed Hendak and the slaves and taken back Nalia's keep from Torgal. The party's levels ranged from 9th to 11th. Everyone has a +1 magic weapon except Minsc has +3 Lillarcor and Anomen has the +3 Flail of the Ages. I didn't have Azuredge, Daystar or Prot. from Undead scrolls.
I cleared out the graveyard in Athkatla knowing that I would encounter nothing but weakish undead. I agree with Wes. The encounters required more buffing up and a little more strategy. I noticed much use of the fear spells (Horror, etc.) which makes sense. After all, most characters should recoil in terror when confronting undead. The Skeletal Warriors were the best, casting Horror and then engaging in melee. I didn't notice much difference in the Mummy. Of course, I immediately engaged him in melee to avoid any spells being cast my way. I do remember some Shadows (I think it was Shadows) casting Ray of Enfeeblement and taking out my PC who couldn't move. That required a reload or two. Basically, weakish undead powers are more challenging but not impossible. I would recommend using Remove Fear/Resist Fear for every encounter. Buff up and use some potions.
Finally, certain encounters in Spellhold or the Umar Hills could be quite the challenge. I would thnik that prot. scrolls, Daystar, Azuredge would tip the balance in your favor. After all, you can always lower the difficulty level and use Ctr-Y to balance out the encounter.