Break the workbench and make the refinery. FYI the refinery does damage to anything near it unless you build a room for it with black marble and or iron.

The Black Forge is a big upgrade, I know it doesn't seem like a lot at first, but Krom and Arbalest are two of my personal favorite weapons from the Mistlands. Your suspicions are correct, a major resource is still missing, but you're very close. Odin would be proud of your progress!

Did you get back to that last Dvergr tower before the sap extractor despawned? The soft tissue boxes and extractor crate break much more easily than the ward. I think if you would have hit the tower one more time the Dvergr would have turned on you, that's what the you're on thin ice warnings were about. Close call, though it looked like most of them had died in battle by then.