I've been playing with the smallest version of the Handy Sharp sharpener for about a week know and so far it's my favorite touch up knife sharpener. The small version fits easily on my key-chain (the little orange thingy):
I was catching up on my youtube subscriptions a few weeks ago and found this little gem on the Equip2Endure channel and had to order one. While the orange handle is cheap plastic the sharpener is made out of tungsten and has no problems working over a dull blade and the best part is it's on my keyring so I haven't forgotten to bring a sharpener with me since I added it to my EDC.
The official website is: {
http://handysharp.com/ } and at $8.00 (without shipping) I think it's a good deal.
~Brad~