Draw a Kingdom Hearts Keyblade

This will teach you how to draw existing Keyblades and create your own.

Steps

Pick your Keyblade. If you aren't drawing an official Keyblade, then pick a Disney movie (or something else) to model it after.
Get a picture of what the existing Keyblade looks like, or get a mental picture of what you are going to make up.
Draw the handle first, because it is the easiest. If you are making a Keyblade up, the handle can be any shape, but it looks the best if it is an oval with a line in the middle. Draw an oval, a line going through the middle, then another oval (slightly larger) outside of the first one. When you color it in, you can add cool designs to the handle.
Draw the shaft. If you just want it to be simple, it's just 2 narrow lines. If not, outside of the 2 thin lines, there would be 2 more lines much wider apart. This gives room for decorative design. The 2 narrow lines will be colored in, but in the wider lines, you can do designs, patterns, or ribbon strips going off the sides. Get creative!
Draw the blade. It can be 2 spikes, 3 spikes, or an intricate design that you make up yourself. As long as it looks sharp, it looks good.
Add the keychain. Draw some ovals coming off of the handle, then a single shape that has to do with what you are basing it off of.
Add color and design and it looks great. Now come up with a name that has something to do with whatever it is based on.

If you want to combine keyblades (for example, in the Kingdom Hearts 2 Keyblade, Decisive Pumpkin, it looks like Halloween and Christmas both occupy the design). If you want to do this, the best way is to have half the shaft and the blade be one thing, and half the shaft and the handle be another.
Combining Keyblades is hard, but fun, so try it after you have had some practice.
If you know any Kingdom Hearts fans, you can make money off of making designs for people, scanning them on to a computer, and emailing it to them as a picture. They can use it as a background, icon, or avatar! (See warnings below)
If you have Adobe Photoshop, you can scan your pencil drawing in and add exciting effects.
Once you've mastered keyblades, try keybows, keystaffs and any other weapon you can think of.