Wow! Thanks for all the great information everyone! To answer some of the questions that came up (and ask some more of my own):
Douglas: I'm definitely looking for something freehand. I'm interested in (and motivated by) developing the skill needed to effectively sharpen freehand. It seems the discussion went this direction organically.
Also Douglas: I hadn't considered the 'sharp enough' idea, or the idea that a knife could be 'too sharp'. That's really good information and will help guide my sharpening journey I suspect. Thank you for sharing that.
Ben: I'm intrigued by the idea of using a natural stone, but I've also read - and you mentioned - that they should really be used with a sharpening oil instead of just water. I'm not sure what sharpening oils are derived from, but for food prep knives I expect I'd feel more comfortable with water. Can a natural stone be used successfully with just water? What are the differences between oil and water with these stones or sharpening stones in general? There's also the issue of oil mess as mentioned in a video posted in the PEP Knife sharpening BB (https://permies.com/wiki/105867/pep-tool-care/PEP-BB-tool-sand-knife
Also, what are the general qualities of natural/synthetic/diamond? I gather that diamond lasts longer, and cuts faster, and that natural stones have some variance in grit. I assume there's more nuance than this though.