After entering the fort you will be lead to the elder of fort. After a short speech he will send all of his guards to attack you. I suggest that you have the steal/pickpocket skill by now or have plenty of health potions. After beating all of the guards and mercenaries you can then more safely search around. There are plenty of boxes and barrels that you can break to find random items. Some of the chests in here can be a bit difficult if you don't have a good lockpick/disarm trap skill. You will basically fight unlimited monsters/guards here. The first group is the largest you fight though. After searching around and killing the 2 main people, you will get the keys for the rest of the castle. After searching everywhere to get the chests and barrels/boxes you can then head to the basement. Going through the bedroom (with all of the bunkbeds) you will make your way to the jail. You need to hop across the small platforms off of one of the first rooms to make it to the actual cells. You can then free the prisoner and he will tell you about the armor. It is in a secret room in the tombs. After making your way down to the tombs (the lift that goes down from the lower level... duh) there are 2 doors. The door on your left when first riding the lift down is the one where you would originally get the skill lever. The other option is to simply open the door ahead of you and pull the 2 levers to open the second door. Pull them diagonally starting with the one on your right when entering the door. The stone door should then open. As soon as you enter this room you will see a platform at the back across the water. Ignore it for now. Jump into the water on your right as you enter and dive down to find a secret tunnel. Part way through this tunnel is one of the skull levers. If you didn't bother getting the other one first... then use this on the right lever pad on the platform in the back of the first room. This will lead you to the armor. There are 2 doors on the left and right sides of the lever platform. They each contain 2 doors with many monsters and 2 treasures per door. All treasures contain random items... some can be good so I suggest getting them. On the right path at the second door is where to find the armor. You look on the wall of the second room on the right side to find a button. Press it to open the way to the armor. After getting the armor an elder wraith and a few skeletons start to appear. Kill the skeletons to make it easier to maneuver and kill the wraith. After killing him simply make your way back to the entrance and leave.
Also... for people looking for the first lever... taking the left tomb entrance.. once you reach the small side area with the coffins look to the opposite wall to the right a little ways to find a block that can be pushed to open the wall where another treasure and the other lever are.
NOTES: Do NOT close any doors behind you when entering a room. Most of them you cannot open from the other side. If you have normal monster spawn rates on easy difficulty you might encounter a fair few monsters at one time when in the tombs. When you kill a guard that is using a bow he will drop it so you can take it. If you get close to any guard he will instantly pull out and elven sword. Range a guard from a distance for him to drop his bow. Use only items that give you no penalties.. they will kill you here.
Recommended: Strongest sword that you can buy in the elven weapons shop, strong bow/knives/shuriken, and plenty of health and cure poison potions.
Hope This Helps.