Make the shape of your items, in pitch black. You don't need colors in a silhouette, as you are copying the bits other than the black.
Here are some images that might make it a bit clearer:




The bottom one is a silhouette.
The middle one is the block (texturemap we're using)
The top one is the result of the silhouetting.


This is the finished result, with all shading applied.

Here's a texture mapping trick I use.
Make silhouettes of your swords and tools.
Copy the transparent bits of the silhouettes and paste them onto the block of that material.
Add the handles.

Remember to experiment with lots of different effects. Knowing what the effects do is an essential part of making a good texturepacks.