Hello all,
currently you can't really implement any changes to the shape of items. you could design it in say 3dsmax, but so far you wouldn't be able to put it in game.
You can modify sword and blaster models and get them back into the game!
I did a G11:
http://home.comcast.net/~cchargin/kotor/mission-g11.jpg)
Orsan did an E-11 blaster and a Boba Fett helmet. His site is all in Russian, but you can find it.
http://kotormods.t-k.ru/)
As stated by Darth Dex goto:
http://www.lucasforums.com/showthread.php?s=&threadid=122049)
look for my name: cchargin and you will find the kotor model tool (mdlops). Then look around some more in the post and find all the other tools you should have (like kotor tool) and a bunch of cool mods.
For a gun I blade I would make 2 items that use the same model. 1 item would be a blaster, the other item would be a sword. Then in game you equip the blaster model to shoot, then when combat gets close you equip the sword version. Think of it as changing your combat style to suite the situation.