Who doesn't want a fantasy battle axe for their very own. This battle axe will have a built-in high frequency resonating generator that will increase its impact force by 10 fold. Perfect for comic cons, cosplay or a great wall display. There are 100's of ways to build a battle axe. This is just one way to build a battle axe especially if you have some existing parts. If you are starting from scratch, you have more freedom in designing but it will take more time.
When I design anything from scratch, I always try to use the best materials I can find. Nothing beats the feel and look of metal and wood for an axe (if done right). Generally, I don't recommend 3D printing for weapon props. The parts tend to be too light and have obvious printing layers. You can address these issues but try to use metal when possible. Working with metal is not easy but the end result is always satisfying.
(P.S. I own several 3D printers but I find myself rarely using them)

Supplies

A large piece of metal - literally any shape you can find that suits you.
18 inch length of hardwood, exotic if possible.
1/2 inch threaded rod or long bolts.
1-1/4 inch diameter aluminum
Rub-n-Buff
Good quality thread (black)
Super glue (standard, not gel)
24 inches of leather strapping

Step 1: Secure a Brass Casting

Here is a brass casting I've had sitting around for many years. Weighs about 5 pounds. This shape will work fine for a battle axe. The casting is somewhat rough and will have to be sanded, polished and then hand peened. If I didn't have this piece, I would have to cut out a similar shape from a solid block of brass.
If you don't like brass, any interesting piece of metal will work fine. It doesn't even have to be axe shaped. Maybe a club or large sphere.
So go out and find an interesting chunk of metal and see what you can make!

Step 2: Boring Out the Top

Here the top is bored out to create a space for the high frequency resonating components.

Step 3: Machining the Top Cap

This old 3 inch diameter brass screw nut will work for the top cap. It will have to be machined inside and out to fit properly. The hex portion is machined into a pleasing dome.

Step 4: Sanding the Blade

This casting is a bit rough and needs to sanded and polished, then peened. This could be left as is for a more rustic, battle worn look but I prefer a more polished finish. After a few years the entire axe will start to take on a nice tarnished, aged look.

Step 5: Making the Handle

I had a suitable piece of Ipa wood that is dense and hard. It holds up well for tapping threads. Bore out a recessed hole for the head shaft. Then drill and tap 1/2-16 threads. On the other end drill and tap 1/2-16 threads only.
Each end will be machined to accept a heavy brass collar.
Now machine 1/8 inch wide grooves about 1/16 inch deep. There is no need to measure these grooves, just eyeball your way across the handle.

Step 6: Wrapping the Handle

As with any weapon, there are 100's of ways to make a handle. This is my favorite! This handle is now machined and grooved. Each groove is now going to be wrapped with a good quality black thread.
Apply a very small amount of super glue along one side and place the end of the thread into it. This step just holds the thread in place so you can wrap it tightly.
Now wrap the thread tightly so there are 3 to 4 layers. After wrapping, apply a very small amount of super glue to hold the thread in place. Use an x-acto knife and cut the thread flush to the side of the groove.
Now completely saturate the entire wrapped groove with super glue. After a few seconds, use a soft cloth and tightly burnish the groove in the direction the thread was wrapped.
This does 2 things. It forces the super glue into the thread and removes any excess. When you are finished, the thread is locked into place and has a protective finish.
Don't worry about any super glue outside of the groove. Since the groove is 1/16 inch deep, a final light sanding removes any burnished in super glue without disturbing the wrapped thread.
After all grooves are wrapped, burnished and a final light sanding, apply your favorite wood oil.
This process is extremely durable. I have similar handles that are over 15 years old and they look like they were done yesterday!

Step 7: Machining 2 Brass Collars

Here I can reuse 2 large brass nuts for the collars. Each measures 1-5/8 inch across at its widest dimension. First machine the inside to the proper diameter. Then machine the outside into a pleasing barrel shape.

Step 8: A Finished Ipa Handle

Here is the finished Ipa handle with the 2 brass collars. Grooved, wrapped, burnished, final sanding (240 grit) and oiled.
Here is a dagger I made about 8 years ago using the same process. 100's of people have handled it and it has held up very nicely.

Step 9: Machining a Collar Washer

A collar washer has to be made to keep the axe head centered on the handle. This was machined from aluminum.

Step 10: Handle Lanyard

I will use a 2 inch diameter solid brass ball for the lanyard end. This will give some proportion to the entire axe. A 1/4 inch hole in the very end will allow for leather strapping.

Step 11: Making the Resonators

This battle axe uses high frequency resonating technology to increase its striking force 10 fold. A single blow generates considerable vibration when used and if not dampened would be unbearably painful to the user. Dual anti-resonators must be installed to counter act the vibration. These are machined from 1-1/4 inch aluminum rod and are 3 inches in length. Cooling fins are cut every 1/8 inch and about 3/16 inch deep. Later, the 2 anti-resonators can be anodized and the leading edges of the fins remachined to reveal a nice contrast.

Step 12: Peening the Axe Head

For a more detailed and unique look I will peen the entire axe head. This will take several 1,000 blows with a ballpeen hammer but will be worth the effort. After peening, I will use some rub-n-buff on the entire head. Then use steel wool to reveal shiny brass highlights.
UPDATE - I estimate it took over 8,000 light blows! Whew...

Step 13: Final Assembly and Finished!

Here is where you can do any final sanding and polishing. When I use brass or other metals, I never treat or coat the surfaces so a nice patina will form in a few short years. The only exception is when I anodize aluminum.
The peened brass head had one application of a dark rub-n-buff. Then lightly buffed with steel wool to reveal the top portion of the peening. I estimate about 50 percent of the rub-n-buff remains. This technique really has a stunning look and can be used on most metals. After installing the anti-resonators and leather lanyard, the finished battle axe weighs just about 7 pounds. This is one serious weapon and will definitely go into my personal collection.