I'm still having issues with my mouse in Dishonored 2, but it sounds like the latest patch did some interesting stuff with the difficulty. The RPS story has some more information:

The Mission Select works as follows:

…with Mission Select, you’ll be able to select and replay any mission you unlock after the update is installed, retaining the status of your playthrough at the start of that mission – giving you a better shot at nailing that Ghost or Clean Hands run.

There’s an Ironman mode to play with as well, disabling manual save and loads, and leaving you to live with the consequences of your actions, and to curse that one guard who always falls down the steps and breaks his neck when you send him to sleep.

I'm not sure how it'll affect people like me who haven't gotten that far into the game yet, but the "custom difficulties" setting also sounds interesting. It sounds like you can set a slider to tell how many enemies will attack you at once when you're in a fight. I usually play these games in stealth mode, so I don't wind up getting into any fights, but it's still a weird thing to patch in. Anyone try this yet? Does it affect achievements?