Grimrock

to have the sword of Nex in possession or equipped

to have the Fire Sword in possession or equipped

to have been to level 7 by other means, previously

You need to have the sword of nex in you inventory (proved)
Nothing should be on the floor in front of the door (proved)

You should have visited the level 7 by falling into a pit or simple by going down the level 7 stairs (still pending)

Inside the "pit puzzle" room in the Halls of Fire, where you claim one of the Round Keys in the dungeon, you'll be able to find some fancy loot. Once you've claimed the Round Key, pull the Torch from the sconce nearby to raise a platform. This is the key to uncovering this secret. Go back to the first switch in the sequence, and run it again, this time going all the way around the column. When you reach the position where you claimed the Round Key, press the switch there and then take the new platform back to the main area. Run as fast as you can around the pits in the floor, and turn back to the central column. You'll spot a raised platform - rush over and hit its switch, and at last, a hidden wall section will open, revealing a Uggardian and a worthy reward.

Reward: Sword of Nex, Ring Mail