The hard difficulty is definitely hard. That's why the bosses kill you in one or two shots. That is also why, as the tips suggest (those tips that appear when you load and save), you should go elsewhere before coming back. In this case, you should probably go outside of Aleroth into the woods and kill a few orcs. They're relatively easy and give a buttload more experience than wussy skeletons. You can get to 10th, 11th level easily by killing most of the orcs around town. Some of the boss orcs are a bit more difficult (Wardrummers), but just run away from them and keep killing the regular orcs. By the time you're ready to go back to the Catacombs, you'll find that the "bosses" are a lot easier.
Hope this helps!
