Matras:
I am going to tell you this secret because I only found out about it thanks to your help. Apparently, there is a passage that leads directly to the second tower of the Steel Citadel. I found it easily enough, and I think you will, too. In fact, if you want to use that passage, go speak with Deltuva. Since you helped me by obtaining the blueprint, I know he will help you. May Maphr protect you!