Would it be illegal to create lightsabers for Oblivion?

yes, absolutly. If you feel the need for an ultimate sword, just do some serious enchanting.

I don't think so. I mean, it's not copyrighted or anything... or is it? Morrowind had a lightsaber mod...

Well, if you go for a Lightsaber, I think it is illegal. But there should be no legal problems in creating some sort of energy sword. Things like that have been around in sci-fi long before mister Lucas decided he wanted something more flashy than steel. (The result looked like a radioactive club that glows in the dark instead of a noble sword, but that doesn't matter.)

Now, don't trust me blindly, cause I am too lazy to learn the laws beyond the don't steal, stop before red, don't kill, don't drive on the left side of the road variant.

look at the starwars mod on the theelderscrolls forums

Yes well .. there were the Morrowind light sabres, so I wonder how they got around the legality of that? Nobody ever said they were illegal that I ever read - hope not, I had quite a few in one of my mods.

Why not however, design something similar of your own looks, as Jack Cloudy seems to be suggesting. Make it uniquely your own and call it by your own title. Then no one can say anything about plageurism, but only how creative you are. If you are going to use an existing sword model in the game, I think people achieve those moving fiery effects on the gamma level of the model. Does anyone know if that is correct? Anyway, there are programs designed to assist you in adding the moving ethereal/fiery/etc. effects to the models.
One of the coolest swords I ever downloaded was a supposedly "crying sword" and you could actually see it dripping water at its tip - very cool.

*rock falls from the sky and pigs start flying...* Ok, if you want a glowing sword take the Uber enchated ones some Dungeon Siege I and upgrade: The size
The glow
The shape of the sword...

legality and copyright is only an issue if you attempt to make money off the mod. you can pretty much make anything you want as long as you don't sell it to multiple people. you can even sell it once, for example, you could make a sports team t-shirt for someone and as long as you make one and sell only that one, it's legal. same applies to this sort of thing. so don't worry no one'll get in trouble. long as you don't ask for money.

Well that's right good to know, and if I get in any trouble concerning this method, I'll be sure to say The Devil made me do it!!!

ROFL!!