The Cursed Crusade

This achievement is very similar to those of the weapon progression achievements except these are your skills for your character, not moves for your weapons. Here are a couple of things to keep in mind when trying to finish this achievement:

• You will not be able to level up all of your skills in one playthrough. With this in mind, you must venture into the Nightmare playthrough in order to finally finish this achievement, whether or not you plan on finishing the entire campaign on Nightmare. 
• I suggest focusing on being able to hold onto the curse for a longer period of time first because of its ability to help you slaughter enemies in a much easier and more efficient manner.