Well, the fuses are described on the underside of the fuse box in a diagram. I think this is how Nissan traditionally does it since it was the same on my 2002 Pathfinder.
Some of the descriptions are a bit cryptic though, so it's not always clear what each one is. Even the service manuals don't do a great job of describing the purpose for each fuse.
I can tell you from my 2011 Armada, which is probably 99% the same, there are two fuse boxes under the hood behind the battery, which you obviously know about. The one in the back is hard to reach but shouldn't need to be accessed as often I'd guess.
There's also one in the glove box on the right side.
BTW, in my 2011 Armada, it does describe the locations of the fuse boxes, but leaves no description of each fuse, leaving that to the covers for the fuse boxes.