I have used all manner of stones, steels and sandpaper for knife sharpening over the years and both my wife and I have eventually settled on one favorite sharpening tool –

I get 'em here –
https://www.ragweedforge.com/SharpeningCatalog.html
This is what Ragnar says about 'em –
"Two Sided Diamond Plate from Hewlett
If I were starting over, and buying a single tool to sharpen my knives, this is what I would get. It has a medium (600) surface on one side and a fine (1800) surface on the other. It's 4" long, 1 1/4" wide, and less than 1/16" thick (.055"). The plate and it's plastic sleeve weigh about 1 1/4 ounces. Made in the USA. $19
The two sided diamond plate is now akso avaialble with coarse (270) and medium (600) grits. This would be useful for taking out nicks or restoring edges. The price is the same $19. If you would like this option please to be sure to specify "two sided diamond plate, coarse/medium". If you don't specify I'll send the fine/medium.
I also have a single sided plate in this size in 600 grit. $10.
If I were going to add anything, I'd get something for a super fine finish or strop. The Viking whet stones shown below would be excellent. The inexpensive ceramic sticks listed below would also work.
The single sided plates shown below are a close second, and actually fit a wallet better. I personally prefer the slightly greater length however. "
When I got my first one my wife tried it out, then walked away with it and slid it into her purse! I had to buy myself another. We both like sharp blades and use knives all the time, especially since we butcher most of our own meat.
She carries hers in her purse to this day.
I haven't weighed mine, perhaps I should. But, if I were to carry a real belt knife on a trip, or reckoned I was gonna need to be resharpening my blade, – You know, if I figured I needed it – This is what I'd take.