I am unclear from the tooltip of level 5 Detect Hidden if it's required for you to open secret doors, or just a useful aid in helping you find them.
I ask because I found 4 of 5 lorestones in the Gorguath runes. I could see the last one up above the room where you fight the Thresh, but couldn't figure out how to get to it. Looking around online for the answer, I saw that you apparently need to go through a secret door to get the one I'm missing. However, I've run around the dungeon like crazy trying to interact with walls and such hoping I'd be able to open a secret door, but have had no luck, making me wonder if it's even possible to open the secret door without the skill.