I didn't know they shipped the bonus stuff in unity engine. Sorry for that.
XTool's unity plugin works only on BUNDLE files and some other files without file extension, mostly located in "*_Data\StreamingAssets\...". The plugin does not work on *.assets and *.resS files in general.
I checked and yes, you can use unity plugin on the following files "ArtOfOblivion_Data\StreamingAssets\AssetBundles\W in\*"
However you have to use the correct LZ4 library in this case. DSG does not do this for you, you have to manualy write it. Also you have to use level 12 on this files
Code:
xtool:c32mb:munity,lz4hc,l12:lz4_193:dd3+lolz:dtb1:d122:mtt1:mt16:mc1023
Also, for the MP3 files use the 7z dll mp3 plugin. Personaly I use mp3c.