How do I complete the torch puzzle in the secret chamber in Castle Dimitrescu?
Solution 1:
So I managed to stumble across a reliable solution to this by accident. You can light enemies on fire with one torch, and then use those burning enemies to light the second torch. You're actually required to do this for another optional puzzle much later on in the game, so I wish I could say I had the brilliant idea to apply the same solution to the castle puzzle, but in reality I just stumbled into it purely by accident.
What you'll need to do is to lure at least one enemy into the secret chamber with you. This shouldn't be hard to do, as there will be about 3 or 4 enemies on the path from the kitchen to the chamber, so just make sure you leave one of them alive. Then you just need to blow up the broken wall with a pipe bomb as normal, and fling the leftmost torch into it (you can easily just push it in). Once that's done, just whack the enemy with the lit torch (or let them wander into it), and then just whack them with the unlit torch to solve the puzzle.
I wasn't able to record video of this, since I didn't think to record until much later on, but I do have the automatically recorded video of me lighting an enemy on fire for the Medium Rare Achievement for a puzzle later on in the game: