I'm a total noob at modding...so bear with me.

I tried to make a custom lightsaber using Achilles' saber tutorial. Everything worked out...I changed everthing correctly until I got to editing the .mdl files with the hex editor and the .uti files with the GFF editor.

Gff- I changed everything correctly, it's just that when I save, instead of saving as a .uti file, it saves as a .gff file that doesn't work when put into the override folder. I'm using the Gff editor with the icon with a picture of buildings. (I don't know the name.)

Hex Editor- I'm using the XV132 free hex editor. Achilles' tutorial says to search for "01" and change it to "02". He said there were only 4 references, but each time I searched and changed 01 to 02, I found about 20???

Also, could it be that the tutorial was made for SW:KotOR and not SW:KotOR TSL?

Any help would be greatly appreciated.

Use Kotor Tool to edit uti files. It has a built-in uti editor.
For your lightsaber problems, what are you trying to do?

I'm just trying to name a lightsaber like "The best lightsaber ever" and name a crystal and put it into the game as a start to modding KotOR.

Thanks for that tip.

Yeah, just edit the uti files of the lightsaber and crystal you want to rename. It's pretty self-explanatory using Kotor Tool. Just remember to save your file with a different file name.
For example, if you edited the blue saber (w_lghtsbr_001.uti) to call it "Super Saber," save this new file as w_lghtsbr_012.uti so it doesn't replace all the blue lightsabers in the game. The same goes for the crystals.

In order to get this new blade in game, you'll have to script it in to a location (footlocker, corpse, container) that you choose.