I can't find a source on this at all, but I'm 95% sure it's art done by astroguy2, artist for the Queen's Blade Struggle manga. It wasn't on his pixiv, nor can I find it in any of his books but the style for the eyes as well as the expression fits with what I've seen from the manga.

So, I'll leave it up to the mods for now.

The original size of the image is: 633 x 900 (.jpg) / 1646 x 2399 px (.psd)
Added resized tag.