Ahh, then I say move along, because those chests were meant to be teases for what's to come next.
As for the golden key, you get it after/around the time when you can get to the auction house, which is around chapter 4.
so where is it exactly?
...I'm not sure! :D
I have honestly forgotten!
does the kobold burrow count as finding one of the black knife shards?
Nope. Only those that are optional are.
