So I come across the Statue and she talks to me, blah blah blah.....

I make it so that quest is the only active one, click on it to show location on the map, fast travel to Rebel Cairns cave, very small with a single room and a pedestal...I click on the pedestal and it says "None of your weapons fit this slot"

wtf is going on here. It's the ONLY place highlighted on the map in regards to this quest. I went back to the statue and saw a large temple or whatever nearby, tried getting in just incase it was relevant to this quest but it says I need a key to access.

Help!!! I'm 65 hours in and haven't come across any quest problems, until now that is. :facepalm:

Mine tells me to go to a torture rack in the DB safehouse. I can't do anything with it though.

Hmm, odd indeed. Hopefully others chime in and give some input. I've obviously moved on to other quests until some answers are given.

It seems that you had quite a bad luck since the location where you have to go is random. The location that you were told to go requires Red Eagle's Sword to open the door, which you acquire during another quest.

The Red Eagle quest is given to you by reading a book named "The Legend of Red Eagle", so you'll first have to find that book. Hope you understand what I'm saying, it's really quite confusing, so good luck