Ah, UltraNoob Error Number One! The oldest gaff in the book! I've done it myself.
You DUPLICATED the sword and, hopefully gave it a new name? I always start things with _shb_, then I can find them easily later.
So, _shb_Stainless Steel Sword, name displayed in-game "Stainless Steel Sword".
So, you should have made a copy of the mesh and the textures and given them the same name as your sword. Then, that texture is unique to that mesh and both are unique to your item.
That's how I do it:
_shb_Stainless Steel Sword
_shb_Stainless Steel Sword.nif
_shb_Stainless Steel Sword.dds
Otherwise, you just change all the steel swords in the game. Luckily, it is only saved in your esp file, so deactivate th mod and go back to vanilla. If you change the names of what you have copied, that should work fine as long as they have different names to vanilla.
Then you have to find a way to get the sword into the game.
Using the console and typin
Help "stainless steel" should give you the code for it.
~.~