All you need for this is: a bat or a tonfa (I used my homemade tonfa), a circular saw blade, a hacksaw, a screw, a hammer, some tape and maybe a screwdriver.
Video Tutorial up now, watch it above ^^ :)
You can watch this video its about my weapon: http://www.youtube.com/watch?v=I7gV53Bb67I
Step 1: Tonfa or Bat.
Take your tonfa or bat and cut through the top with a hacksaw, you may need a screwdriver to open up the cut to fit the blade in.
Step 2: Add the Blade.
Now add the saw blade, as I said you may need to put a screw driver in the slit as you put the blade in, make sure the blade has a small hole (to fit a screw)
Step 3: Hammer Dat Screw In.
Title explains it, hammer the screw through the small hole.
Step 4: Now Add Tape
I added tape for three reasons 1: It looks cool 2: It gives more grip 3: It feels like it holds it together a little