How would you sharpen one of these things

A friend asked me to sharpen his axe and this thing. I was able to avoid the axe but am obliged to sharpen the thing.

How would you go about doing this? The flattish part is OK, pink brick will do good here. But how should I sharpen the curved part?

I have some really cheap Bauhaus stones that can be destroyed for the purpose of sharpening this curve. But I just do not know what is the best way to get to the bevel with the stone.




In comparison with Konosuke 210 HD.

Hi!
I have a similar tool, but smaller. The only possibility for me to sharpen this thing is by using the spyderco sharpmaker. That's the only reason why I still own one.


Mack.

Sandpaper

I agree: Sandpaper around a stick/dowel.

Jesus that side-by-side picture makes a Kono HD look sexy as hell, haha!

What is the " Thing" used for? That is an interesting knife for sure.

Rounded corner of a stone, as with a tourne knife.

Is it a single bevel or double?

They make special (handheld)stones for sharpening curved blades on secateurs.

You can try to track one down or use any sharpening device
that has a curve or with a narrow enough of a flat.

The usual shape for is long and thin rectangle,
w/ a semi-circle face on one side
to handle a curve in the blade.

Try japanwoodworker.com or just use sandpaper

I would use a scythe stone.

I dont think a traditional stone would work.

This is potentially what you should look for.

http://www.leevalley.com/en/wood/page.aspx?p=33012&cat=1,43072,43071&ap=1

https://youtu.be/OYhRCDmD41Y

Khao men scythe stone. Miles is always generous with sending a few to use as slurry stones when you order full size Thai benchstones from him. Where are you located? I've an extra I can send your way.

Form stones.

DMT W7 in extra coarse and fine

Thanks for all the suggestions.

I will start in a way shown in the video link from TheCaptain. I have some really bad and already destroyed stones. It will not hurt if I get them round.

I will let you know how it goes.

So finally I could find some time for The Thing

I prepared the tools:
2 bad cheap stones for the curved part
Bester 220 - pink brick
Naniwa pro (chosera) 400
Naniwa pro (chosera) 1000

Sorry for bad picture:



And then I started grinding. First on the curved part with cheap stones. I was using the method shown in the video from TheCaptain. It worked quite well and circular motion soon produced the burr. I repeated it on the other side. After that I used the other cheap finer stone.
I must admit that I was not so thorough and did not make big efforts to remove all the burr in this area.
Then I moved to the "straight" part. Here the job was really easy. Bester did a good and quick job that was finalized on Choseras. As expected the sharpness of this part is way superior to the curved part.



The coarse stone used for the curved part really took the hit:



This is what 5$ stones should be used for