You might enjoy The Black Company, which is a series of books by Glenn Cook. If I’m not mistaken he was mentioned as a source of inspiration by the devs (citation needed). I know there’s a black company reference in game in the form of a competing band called the black company.
This! To be honest even in-game texts seem to be inspired by this series. Anyway, the series is really good but sometimes exhausting to read as it is dark fantasy and each part of the series is written by other chronicler of the company. I mean the real author is only one of course, Glenn Cook but in-book there are a few chroniclers, so you can watch an action from many perspectives. Just sometimes you may find yourself in a position when you like one of the chronicler’s writing style more than another. :D I am reading the last part of series right now and I am really amazed that I have been involved so hard into its atmosphere. Totally worth of reading!
I wish the devs had added Black Company’s banner in game. :(