First and foremost is the permanent shuttering - for the season being over is not the same as the series ending - of Clive Owen's magnetic Dr. Thackery. Why the other doctors in the room didn't move a little more quickly to disobey his repeated orders and intervene to save him is not clear, and not satisfyingly explained by their fear of going against his commands. On the other hand, there was likely little if anything they could have done after he nicked so crucial an artery. And so the anti-hero hero of The Knick dies of a nick self-inflicted.
The other big event was the marriage of Cleary and (former) Sister Harriet, which happened off-camera - actually, she put on his ring, which I suppose makes them married - but was the nonetheless a triumphant event. Or, would have been, had not we learned a little earlier that Cleary, in his love for Harriet, had told the police about the abortions she had been performing, in the hope that exactly what happened did indeed happen - she would be thrown out of the sisterhood and into his arms. On the other hand, it was an act of desperation born in true love, so perhaps there's a little nobility in it after all.
There's no nobility in eugenics, and the talk of taking the ocean liner to Germany to further that work was chilling indeed. So was the the way people get away with murder in this narrative, not only in the finale but throughout this season.
But there's hope for Algernon, whose wounded eye will not let him resume his profession as a surgeon but leaves open a career in the new psychotherapy, which promises all kinds of possibilities for the next season.
Assuming there is a third season, which hasn't been formally announced as yet. I'd certainly like to see one - and hey, given that no one cut Thackery's head off, it's even possible that we may see him alive again.
See also The Knick 2.1: Playing Off Our Present ... The Knick 2.4: Spirochete
And see also The Knick: Paean to Scientific Method ... The Knick Sneak Preview Review 1.8: Good Loving, the Fix, and Typhoid Mary ... The Knick Sneak Preview Review 1.9: Sacrifice ... The Knick 1.10 Sneak Preview Review: Fallibility