In KoTOR Tool, either go to Blueprint Items and double click on the item you want to edit or press Ctrl+O to open a file from your override folder.
Either way the Item Editor will open, click on the Properties tab and there you can either edit existing properties or add new ones. To make the weapon instant kill, set the Property Name to On Hit, the Subtype to Instant Death and Value to DC100.
As SA said the only way to edit the damage that Force Powers inflict is through scripting, you're best to try simple scripts before attempting Force Powers, take a look through the scripting tutorials forum for good advice.
Last edited by Stream; 01-30-2009 at 04:03 PM.
Reason: Typo by the Keyboard Gremlin