There are a few must haves. dmt diamond stone, i have the older blue/red combo, i would get the diasharps now if i was getting them as big as you can afford 8-12 inched whtever they have now
the next necessity is 25 dollar combo japanese whetsone, use the diamond stone to true_flatten_the whetstinbe after use. when i used it alot i floated it water since i was using it a few times a week
If you want to learn from one of the best, if your in nyc, watch the master at korin in tribeca, Yes theey used to arguie with me about the diamond stone trueing the whetsone, now they sell them. or there is a great book by leonard lee
Tip, when sharpening, ask yourself whats the intended use, that will effect your included angle. for example, i like my 10 inch chef knife toothy, so my angle is a little higher. most people on double bevel chef knife say the included angle somwehere between 25-32, i think 7 quarters is 28.
truth is witrh all my expensive knives Japanese single bevel and german doules, i havent used a whetstone i 10 years. Diamond stones are much quicker and more efficient.
Freehand sharpening is a learned skill that can be mastered if you practice. practice on old poop knives.
On my search for norton white lilly which is oashita stone from arkansa, joel m of brooklyn had a bunch of them. Took the subway there, walked into his massive woodworking shop.... we spoke....he said he had no more for sale. he said you want to sharpen i said sure.....busted out the only knife i had on me a gentlemans folder a spyder kiwi that i just got with a razor sharp edge, he said start sharpening and i did and as i messed iup the blade, he showed me where i was messing up and the process began. over the next few hours i learned alot, still havent gotten my lilly yet but.......