"Fix for a rare crash that could happen when killing a NPC with a possessed rat and spring razor." Out of context, that sentence makes it sound like Bethesda has furthered some kind of twisted research into psychedelic drug-murders. But no - it's one element to a new patch in Dishonored that makes the open-world venge-fest a much more enjoyable experience.
While a number of other bugs have been fixed - primarily those that were present since the game's launch - some new features have been implemented too. PC players, for example, can now play using multiple screens, and settings are now saved while playing on Steam offline.
Here's a list of the other fixes - the possessed rat and spring razor thing applies to the Xbox 360 and PlayStation 3 versions, by the way.
1. Fixes for some interactions with Granny Rags that invalidated nonlethal playthroughs under certain circumstances. (Note: These fixes work even for savegames AFTER the final Granny Rags encounter.)
2. Fix for a crash that could happen during loading/transition between areas - notably near Dr. Galvani's house.
3. Reworked “Choke” interaction to make it more reliable in valid contexts.
4. Fixed minor localization issues (PS3/360).
5. Fixed global post-process that sometimes worked improperly during some missions.