Well, if you want to melt hair off your arm with broadheads so sharp you're afraid to take them out of your quiver (seriously, that dangerous), I just use a progression of arkansas: soft, hard, translucent, and black beginning with soft and ending with black. You have to keep the angles right, and you have to know HOW NOT to switch to the next stone too soon.
Here's a few of my thoughts on the above, however:
1) At first it made sense to buy all 4 as pocket stones (because I was broke): but I found it was hard to get on the bevel before the stroke ended. So I got 10 inch bench stones so I could have a good 8-9 inch stroke. Oh, that was going to be a REAL luxury....
2) I invested $150 into four 10 inch bench stones and promptly found out that my $120/doz grizzlies are not manufactured with a straight bevel: they won't quite lay flat on the wide stones (the middles wouldn't touch). So they couldn't even be sharpened.
3) The fix on the above was to switch back to those annoying pocket stones. Geez, if you are dedicated you can definitely get your broadheads DEADLY sharp on them, but it is NOT EASY.
4) After spending hours honing my broadheads to a dangerously sharp surgical edge, (broadheads so sharp you can miss the deer, and it dies of a heart attack), I discovered that while grizzlies do TAKE a sharp edge, they don't KEEP such an edge. Especially if you use a back quiver (basically just a giant leather-strop). So I was better off not even moving on to the translucent and black stones at all.
5) Knives need really good, harddd, steel (read that as 440 C) to HOLD the type of edge that the translucent and black Arkansas deliver, and most factory, custom, and antique knives DO NOT have this type of steel; and will not hold a surgical edge long enough to do anything useful.
My conclusion was:
A) If you use a back quiver, then a soft and hard Arkansas are all you need, any finer edge will be ruined by the quiver's stropping action anyway.
B) With certain bow quivers, those tantalizing translucent and black Arkansas stones, and the finer edge they produce, begin to make more sense.
C) Some broadhead and knife brands come with a blunt factory bevel and you need a much COURSER stone than soft arkansas to start out with. You'll literally ruin your soft stone even trying. I have an old diamond paddle that I use for such heads, and I also have a pocket stone of artificial variety in about the coursest grit available. They both work well for this purpose.
That's all that needs to be known about buying whetstones.
Here's something you don't need to know, though:
Those lansky and smith jigs work. I almost recommend them*, especially for repairing or re-doing a bevel: Biggest bane of my existence when hand sharpening with a whetstone is a knife or broadhead that lacks a perfectly flat, straight, uniformly angled bevel, and my god, those lansky/smith jigs and a course diamond will fix any bevel out there.
If you order the lansky/smith jigs, you still buy the same stone progression: course diamond, then soft and hard arkansas. (You still need to do the translucent and black stones by hand).
* However, the manufacturing process on the smith jigs is worthless, and you have to use them VERY GENTLY to avoid stripping screws, shifting the clamp, etc. Yet, if used within their limitations, they accomplish their job and do it well. They are just cheaply made. The first jig I bought was defective and I had to send it back. Your money is never going to be well spent with smith, but your edges WILL BE SHARP.