Wooden swords are useful for a variety of purposes: western fencing, kendo, decoration, or even just some rough play. Making a wooden sword is the sort of thing anyone can do, given the right tools, good materials, a lot of time and no small amount of patience.
Choose a sword design. What kind of sword you pick is important, because you do not want to work with thin-bladed swords. No carver wants to put a lot of work into an item that will easily break in two. Choose a broad-bladed sword, like a gladius, long sword, katana or claymore. Avoid a narrow-bladed sword like a rapier.
Select your wood. Most wooden swords are made out of the pleasant-looking rosewood, but if that is not available, any hardwood will do. You will need two pieces: one for the sword and one for the crossguard.
Shape your sword. Unless you have access to a lathe, you will need to do this by hand, carving and whittling the sword. Using pictures of a real example of your sword, carve the one piece of wood into the shape of the blade and handle, then sand it for a good finish. Make sure your handle is wider than the sword blade. That's important in fitting the crossguard.
Using the coping saw, carefully measure and cut a hole in your square crossguard. The crossguard will be sliding down the blade, stopping at the handle, so it should be measured for that part of the sword (presumably the thickest part). The fit must be exact, so take your time.
Slide the crossguard down the blade and fix it into place above the handle, using wood glue or another carpenter's adhesive that is even stronger.
Protect your sword by staining and lacquering it. This will also improve its appearance; but the main point is that, after all that careful manual labour, you will want to protect your wooden sword from the elements. Choose the desired stain, apply it with a brush and then apply five layers of lacquer as a sealant. You will want to use that many layers, since this is a wooden sword that will probably be used to whack things.
Working with knives should always be done with the greatest of care. Wearing thick leather gloves is recommended.