Disclaimer: You may delete this thread if you think it is a copy. The point of this is just simplicity and help.
Welcome fellow WoW player, here's a simple guide to model editing - changing your weapon or shield to *look* like something else. Only you can see the change, but it's still fun anyway to make your weapon look like an awesome epic.
Step 1: Download MyWarcraft Studio (two links below).
http://www.cnitblog.com/Files/linghuye/MyWarCraftStudio_0.10.6337.rar
http://linghuye.googlepages.com/MyWarCraftStudio_0.10.6337.rar
Step 2: Open and Run MyWarcraft Studio.
Things to know: All the models in the game are made up of two parts. An M2 file and a BLP file. The M2 is like the basic model of it, and the BLP is the texture or skin that gives the object it's color. WoW has these files stored in MPQs. There are three of them currently in your World of Warcraft\Data folder: common, patch, and expansion. The way model editing works is by adding another MPQ by the name patch-(3-9 or A-Z). This MPQ needs to contain the M2 and BLP files of the armor you want them to look like, but with the names of the armor that you want to replace them with. This tricks WoW into thinking there is another patch, so that it will use these files rather than the files in the old MPQs for the stuff you changed.
Step 3: Find the M2 and BLP of the weapon/shield that you want to change to something else.
Click on File in the top left, and then Open MPQ Archive. Navigate to your WoW's data folder if it didn't already bring you there. Hmm, now which MPQ is your weapon/shield in? Well, the expansion MPQ doesn't have any weapon/shield files in it, so it's out. Let's try common first. A bunch of folders will appear on the left, but the only one that holds weapons and shields is the Item\ObjectComponents folder. Look through the Weapon or Shield folder until you can recognize what M2 and BLP files correspond to the item you want to change. This may be difficult as some M2's don't show up much on the preview picture on the right. They are organized somewhat by what type of weapon or shield it is. The patch MPQ also has an Item\ObjectComponents folder with two weapon folders and a shield folder.
If you have trouble finding it, WoW Model Viewer may help (http://www.wowmodelviewer.org/index.php?option=com_remository&Itemid=35&func=fileinfo&id=24).
Once you have located the M2 and BLP of the item you wish to change, continue to step 4.
Step 4: Create a Text Document and Copy the Treepath.
Now, create a simple text document on your desktop. Click on the M2 file of the item you want to change and then right click on it. Choose Copy Treepath. Now paste that text into the document on your desktop. Do the same for the BLP (click on it, right click it, copy treepath, paste into document).
Step 5: Find M2 and BLP of the weapon/shield that you want it to look like.
The item you want it to look like may be in the other MPQ, that isn't a problem. Locate its M2 and BLP.
Step 6: Extract the M2 and BLP from the MPQ.
Instead of copying down their treepaths like in step 4, we are going to get the M2 and BLP files. Click on the M2 and then right click and choose Extract File To.... This will default to your WoW's data folder, so let's just save them here next to the MPQs. Do the same for the BLP file (click on it, right click, extract file to..., save to data folder).
Step 7: Create an MPQ and put the files in it with the other M2/BLP's treepath name.
To do this, click on Pack and then Create MPQ Archive at the top of MyWarcraft Studio. It should automatically bring you to the data folder again. Name the MPQ you are about to create patch-(3-9 or A-Z). Now to put the files in it, click Pack and then Add file to archive.... Hit the "..." to the right of the text box and go to the data folder and double click on the M2 file. It will appear in the text box, but don't hit the OK button yet. We need to rename it to the name of the file you want to change. Go back to your text document and copy the full treepath for the M2 file. Paste that into the the text box, and then hit OK. Do the same thing for the BLP file (pack, add file to archive, hit "...", copy BLP's treepath, paste into textbox, hit OK).
You should have a sort of mini MPQ now, with the folder Item, containing ObjectComponents, containing the Weapon/Shield folder, with the file that you want your weapon/shield to look like but with the name of the file you want to change.
That's all you needed to do to change those models. It can be pretty confusing at first, but after doing this you'll have the hang of it for sure. Just hit Pack and then Save and Close Archive and start up WoW again.
(You do not need the M2 and BLP files in your data folder, just the MPQ you created).
Thanks for taking the time to read my guide, I hope it will be useful to any and all who wish to change the looks of their weapons and shields in WoW!