I don't really understand why game developers decided to move all the usual settings UE3 has, from the normal .ini files to the windows registry (is it the 90s again?) and that absurdly ridiculous options.sav file.
Which btw I suppose is both encrypted (since the same settings saved in different times produce different files) and compressed (all in-game settings are stored there (besides the 4 that can be found in the windows registry) and that's too much too fit in just 648 plain bytes)
And then I don't know if it's wwise fault (but it doesn't seem, given borderlands 2 has no such problems) but there's that awful issue where replacing audio files (with those of different languages) lead to no audio and no captions....
For the records, it seems the setting is stored in the registry anyway (HKEY_LOCAL_MACHINE\SOFTWARE\arkane\dishonored in the dword "language") and that (contrarily to the text UI which are in the respective Localization folder) captions are instead located inside the .upk of each level