[@BlazeGamma] That's actually a really good question, so here is a hopefully really good answer. So unique skills are generally things that are specific to your character, if their a drunk then maybe they hit harder when their drunk or take less damage. Perhaps your at the start of a battle you are hidden and can get the drop on your first foe. These are things that reflect on your character and who they are as a person, what background they are from.

Your other skill is a class skill, something your generally has and you can change a little to work better with the roleplay.