Microsoft clearly mentions how to start with Blend in this article without pointing to any versioning limitations of Visual Studio 2013.
I have installed Visual Studio 2013 Express and clearly there is no trace of Blend and surely no external link to download and install it for VS2013.
Would you please let us know with version of Visual Studio comes with Blend and preferably reference where Microsoft talks about this matter?
Thanks
Directly form the Microsoft website
http://www.microsoft.com/expression/eng/
You can download Blend for Visual Studio 2013 with Visual Studio Express for Windows, Visual Studio Express for Windows Phone, and Visual Studio Professional 2013 and higher.
I'm not sure why it's so difficult to find