That's gorgeous! I'm definitely watching that artist.

Here are a few useful things I've come across recently.
Bridgeman's
Constructive Anatomy, which is in the public domain, and you can therefore download for free!

And here's a little explanation of
tangents in composition. I didn't know anything about them, so had to look it up and I found this very useful.
Lastly, this
leather gear site has been a godsend for me. If you ever need references for medieval/Renaissance clothing, scabbards, belts, frogs (it took me forever to find out what those were even called!), etc. this is the place.

If you want to live an interesting life, you're going to spend half of it being terrified.
-Mary Hollinshead