They are clothing files. When I click on them to edit them, I get one of these:
http://i3.photobucket.com/albums/y94/Darth_Anarcus/KOTORIIextractionerror.jpg)
You need to choose to extract them as .tga on export :)
I want to edit their properties, not their appearances.
to edit properties (ie changing bonuses on items) you need to find the .uti files for the respective item
BIFs -> template.bif -> blueprint, item -> item you want to edit