Knife skills

If your knife won't "fall through" an onion in one vertical "chopping motion" or even cut through with some slight effort, it is not "decently sharp" but indecently dull.  That's not only definitional but basic and important technique. 

Sound severe?  Don't worry,  Not only are you not alone in misjudging sharpness, you're part of a vast majority which not only includes nearly all home cooks, but a great many professionals as well.  

The edge on a new OOTB (out of the box) knife is the sharpest thing that vast majority ever experiences.  However, while factory edges are typically usable, they're seldom very sharp.  In order to get on the sharpness bandwagon, you need someone who knows how to sharpen (preferably you'll learn to do your own sharpening), and a knife which will take and hold a good edge.

By my lights, even a barely sharp knife will fall effortlessly through an onion or tomato without effort, a "beginning cut," or a sawing motion.   If effort is required, that's a good sign the knife needs some maintenance -- whether actual sharpening or just steeling.

There are a lot of ins and outs about which knife, when to steel or sharpen, how to steel, how to sharpen, and so on.  We can go as deeply into it as you like.

Try to remember a couple of things.  First, there's no law which says you need to a truly sharp knife to enjoy cooking or even do a passable job.  Second, a sharp knife combined with good knife skills make things a lot less burdensome for a professional and a lot more fun for a home cook. 

BDL

What's happening with the boiling water addition could be a couple of things.

Water from boiling pasta is often used to correct a pasta sauce. You'll see Lidia Bastianich do this in many programs. America's Test Kitchen, Cook's Country, though they usually save some from draining the pasta, not taken from the boiling pot of pasta itself.

Water that's already boiling doesn't drop the temp of the pan as much so things keep cooking along at the proper rate. This may also be done for time reasons pertaining to TV production or to speed up the recipe in general. 

There are boiling water dough like choux paste, bunuelo, various Chinese dumpling skins

A recipe should explain such additions, or at least specify if you add boiling water or not.

You didn't come out and ask any of this stuff as questions, but since your brought this stuff up I suppose you want some feedback.  

I don't know whether or not your stone is any good, nor know anything about your sharpening skills.  But given the context of the conversation so far, I'm guessing the stone is very coarse, and your skills aren't very good.  Further extrapolation leads to the thought that you're scratching up your knives and creating teeth -- more than actually sharpening them; and the increased efficiency is more about a fresh set on a saw than an actually sharpened or sharp edge.

FWIW, "fine edge," in the context of your knife (and knives) means it isn't serrated; nothing more.  Within a technical sense, increasing fineness can usually be read as increasing sharpness -- but there are limits to how far that works.

You should know there are essentially three levels of Zwilling / J. A. Henckels.  Miyabi (which are made in Japan); "Twins" (made in Germany with a logo of two little men holding hands, aka Zwillings); and "International" (made in places other than Japan or Germany, with one little man).   The lowest and crappiest is "International."  Your knives are International, and -- while not horrible within the context of very cheap knives -- suck. 

I don't know which Calphalon you have, but if it's not from the discontinued Katana series it's also pretty sucky, at best.  For what it's worth, the Katanas weren't earth shatteringly good either; and I'm not suggesting you try and find one. 

It's probably not absolutely true that R. H. Forschners are the cheapest knives worth sharpening, but it's pretty close.  Ditto, a Norton combination coarse/fine India stone Although, if you're looking for "fall through" sharpness, you'll want something considerably finer than an India -- a hard Arkansas is probably de minimis.  Again, those remarks aren't buy recommendations.

If you think of your knives and stones as ordinary tools and not magic wands, you'll understand there's a minimum investment in quality and skills required for competent  performance.   It takes some money, understanding and practice to make them work at all well, let alone at a "speed chopping" level. 

If you want to get into this farther, think about starting a thread in the knife part of the equipment forum.  A good start would be talking about what you want to do and how much time and money you're willing to get there. 

BDL

Sharpening gags like the Shark don't sharpen a fine, knife style edge.  Rather they create an edge with a very toothy, saw-like profile.  Those edges are good for some purposes, less good for others, and dull very quickly.  Carbide sharpeners in general tend to be very tough on knives, using them up relatively quickly.

On the plus side, the edges tend to be very efficient at least for awhile; those types of gags don't require any skill or learning to operate; they're cheap; and for everything that's wrong with the edges, at least they're deburred, fresh metal.  

For most purposes I like a (deburred, fresh metal) very fine edge, with as acute geometry as the knife can sustain without collapsing, and as much polish as the knife will hold for a fair amount of work. 

There's no such thing as an ideal edge or sharpening technique.  Each tends to be better for some things and less good for others; and the user's knife kit as well as his or her 'druthers are very important.  In my kit, the chef's knives, petties and slicers for example get that sort of treatment.   But, my heavy duty knives get a robust double bevel and are sharpened to allow plenty of tooth; and my specialty meat knives also go relatively coarse.  Horses for courses. 

BDL