I feel like an idiot, but I just cleared the two skeletons at the start of the Titan Graveyard and then proceeded to find the knight hidden in a cave on the far left, where you go up from the stairs. I'm now stuck an have no idea where to go. I see nowhere to jump, grapple, and all I'm doing is running into invisible walls. Where the hell do I go?
Please help me! I'm stuck in this level too. I was previously stuck at the exact same place you were but after jumping everywhere for half an hour I finally figured it out. Now I'm stuck again!! I haven't found either of the keys for those two spots. I just keep jumping around the islands.
I finally got it. Stand inside the mouth of the cave as far as you can walk. It looks like a dead end but you can walk to the right and you'll enter a room where you get to fight some creeping coffins and get the first key. I wasted so much time on this level.
The island of the far right, where there's a supply of Holy Water and the dead Knight. There's that tiny hole, cave thing on the north side that has a skeleton in it and looks like it goes nowhere, but you can go right into an opening.