I'm also a bit late to the party, but... How did the knife get produced? The mold was found at the abandoned dig site. That is a long distance from the bath, IMHO ruling out the ice knife as a possible candidate weapon. It is true there is salt at the bath, but it makes no sense for the murderer to create the weapon at the bath and then hide the cubes at the dig site. And while it is true that there is a mention of melting silver, the silver from the brazier is precisely the amount needed to recast the knife. All of this leads me to believe the murder weapon is the silver knife, not the ice knife.

I'm also not convinced by Blinkhorn as the murderer. There is no indication whatsoever of him being a rival or having any feelings of vengeance; instead he appears to be looking up towards sir Rodney, feeling honored to work with him and learn from him. He also seems glad to have the chance to continue his work at the bath, which Pitkin was threatening to shut down before sir Rodney's arrival.

Garrow's exclamation that "it didn't work", I took to mean that he expected the curse to be lifted by the death of sir Rodney, but somehow his ritual death was not enough and Garrow is still under threat of the curse. He also appears to have lied about the "knife flying by". How would a curved blade (which is not good for throwing in the first place) fly into someone's eye, break through the bone into the brain, and then fly back out and land in the fire? The knife was not thrown; sir Rodney was stabbed (with considerable force), after which the knife was removed and thrown into the fire. Garrow makes no mention of any of this. Finally, there is his bloody hands - neither of the other two men are covered with blood, so neither could have stabbed sir Rodney.

The key seems a red herring to make the mystery slightly more interesting. Who would have locked the door, and why? Was it sir Rodney? The key is found near his body, but he seems to have no motive to lock the group in. Or was it the murderer? What benefit is there for him? He would only be limiting the number of suspects to three (including himself).

There is another discrepancy the game completely ignores: when you first arrive at the bath, there are four men in the steam room, but only three sets of clothes in the changing room. Did one of the four men arrive naked, or were his clothes removed at a later time? Why and by whom?

The game disagrees with me, but I stand by my conclusion that it was Garrow with the silver knife.