User blog comment:Thedoucheinthenorth/Skyrim alignment charts-verdict?/@comment-4588723-20120801132420/@comment-3472264-20120806001736

I'd say the Thieve's Guild is probably a much lesser version of Chaotic Neutral because obviously when they steal they're breaking the law but they never go any further than stealing but none of the members are crazed or deranged.

The Blades as much as I hate them do fit the Lawful Good category. People of this alignment often follow "Honor before reason" and that's what The Blades are following when the order you to kill Paarthurnax.