Step 1) download Steam on a desktop beefy enough to fun XIV with all bells + whistles.
Step 2 ) Add non steam game to steam (FFXIV in this case)
Step 3 ) install Steam on Surface 2
Step 4 ) on Surface 2 Steam, click FFXIV and click "Stream"

You can play XIV on any tablet which runs steam. Downside is you need your PC on and running steam/xiv, upside, you're not restricted by videocard/cpu of the surface.