Download
KOTOR Tool. This
tutorial will show you where to find the textures. Extract the blade textures for the colour of blade you want to edit. They have the following filenames:
K1 -
Blue - w_lsabreblue01
Orange/Heart of the Guardian - w_lsabregold01
Green - w_lsabregren01
Purple - w_lsabrepurp01
Red - w_lsabrered01
Turquoise/Mantle of the Force - w_lsabreturq01
Yellow - w_lsabreyelo01
TSL -
All of K1's plus
Viridian - w_lsabreDgrn01
Silver - w_lsabreSilv01
Open the extracted TGAs in Photoshop (or free alternative of your choice) and edit as desired. I would suggest following t7's lead and resizing the TGAs to 256x256.