Talk to the fake Dustie on the right side of the smoldering corpse bar. Keep asking her for more money. (You will have to exit the conversation though.)
When you have found Trias sword, go back to him and follow the dialouge like this:121121. Each time you do this, you should get 300000(!) exp (more if you have a wisdom bonus). My NO got 12 lvlups this way!!!
In Curst Revisited (Carceri), you can gain unlimited exp in the warehouse. Talk to Ebb Creaknees and get him to help and then leave. Go back into the warehouse and pause as soon as the loading screen disappears. Scroll over to the right, where Ebb was at first, and he'll still be there. Click on him while the game is still paused, then unpause it and he'll stay for you to talk to. You can do this over and over and gain unlimited experience. It's a slow job, but highly useful if you feel you need to level up.