This was an exciting turn in the story, and right off the bat I'd like to say that the flow between your turns here was excellent.
Even from the opening, I like the mild foreshadowing with something off about the lock -- obvious perhaps, but still adds to the atmosphere. I also think it broadens the world a bit, because it suggests that someone's after Arrento (as confirmed later) rather than Diamantus or Amanita. Another detail I really liked is that Amanita came unprepared, because everything in life isn't a battle and she wasn't expecting one there. Meanwhile, Diamantus lives on a shadier side of life, and has to always be prepared.
The flow of combat was great. I know you have been using your own rolling system to add variety to the combat and it works really well here, with Diamantus showing both strength and weakness. Some of the careful thinking here also added to the tension, like avoiding the second assassin even after he was pinned, because he hadn't dropped the gun. It makes the reader realize, even more than the shoulder wound, that the characters are actually in peril. Having the enemies be competent was also a nice touch. Mooks, goons, or whatever, they had good communication, good reaction, made good judgments when searching. They're all little things that built up an internal consistency which improved the overall product.
Loved it, guys.