Can bad honing technique spoil a knife?

Poor honing on a blade that was already in true can reduce the sharpness, as you have discovered. This happens if your angle is off, and you knock the edge of the microscopic burrs or teeth over, presenting a duller cutting surface.

It is likely that proper honing will correct this, although it may never be quite as perfect as the blade fresh from the whetstone or factory.

In any case, you will not do any permanent harm to your blade with a honing steel (short of using it as a bludgeon), because absolute worst case, you can always have your knife resharpened, or do it yourself. This may be somewhat inconvenient or costly, but is much less expensive than replacing a blade.

Honing steels were originally intended for use on butcher's cleavers, not for regular kitchen knives. Originally honing steels did not have those ridges but were instead smooth. The purpose of a knife steel is the same as for a strop, ie to straighten and toughen the blade's micro-edge so that it's effectively sharper without having to remove any metal as with sharpening.

You should really never use a honing steel with kitchen knives, a leather bench strop is much more reliable and will not damage the delicate edge. You should also never use a leather strop for removing burr, since the burr will rip the leather and then scratch your blade. Linens are what you use for removing burrs.

That said, European knives use really low quality steel, around rockwell hardness 55, which can only maintain a 40 degree inclusive angle. By comparison Globals can hold a roughly 30 degree angle (although they often botch their heat treatments) and higher quality steels can hold as low as 24 degrees or so under normal usage. European knives also tend to have thicker blades, which produce more resistance when cutting things and make it more difficult to get thin slices.

I own a set of Zwilling knives and Zwilling honing steel, and have thoroughly discussed their care with the Zwilling rep.

As hinted in other answer many people don't realise that a chef's steel is not intended to remove material from the knife edge but rather roll the partially curved tip of the blade back in perfect alignment with the overall blade. This means one should take a shallow angle so the steel "pushes" the tip back in position. Too much angle (as I initially did) and the steel will tend to run across the front of the out out of alignment sharp edge and yes, indeed, make the knife blunt by rubbing against the tip. The wikipedia article on this is not bad http://en.wikipedia.org/wiki/Honing_steel

However equally the German style knives, Zwilling included, are by design a relatively soft steel and will go blunt. For me proper use of honing steel returns a great edge for 10-15 times depending on what is being cut. Then I have to go to the sharpener to get blade back in peak shape. Good news is these blades are suitable for home sharpening, unlike say the Japanese style knives. Zwilling sell sharpeners as well as honing steel's. I use an older equivalent of their Twinsharp Select ( see http://www.zwilling.com/en/sharpening-knives-with-zwilling-j-a-henckels-knife-sharpeners.html ) with good results.

Yes, angle, pressure, and movement all go into the process of honing a knife. If one or more of these elements is not quite right, it can lead to a dull blade or worse a nicked and jagged edged blade. Certain knives, IMHO should not be honed at all, say high-end Japanese knives. These knives tend to use very hard cutting edge, which tends to me more brittle and have a steeper angle. All that leads to chipping instead of realigning the edge.

As most people have said, the honing "steel" (metal or ceramic), is really made to realign the cutting edge of micro burrs which occur during normal knife usage. The "steel" is not intended to actual sharpening of a knife. For that you will need to actually take off metal from the blade to expose new or fresh metal.

But all is not lost with bad honing technique. If the knife has a soft enough metal it can be corrected to a certain degree. As I mentioned, finding the correct angle, pressure and movement will realign the edge again. But if the metal is too far gone and has too many chips, then I believe that getting the knife sharpened is the best course of action.

I'll just add to some similar answers but emphasize that if you really want to maintain a very sharp edge, don't use a ridged steel. At best, they'll take a slightly dull knife and rip some microserrations in it that will make it temporarily seem sharper, but those microserrations will gradually weaken the edge and require more in-depth sharpening to be performed sooner. At worst, a ridged steel can put larger chips into your edge, which will make subsequent sharpening even harder to do.

This is partly a personal opinion, but ridged steels are common and people buy them because they are more interested in making a knife work a bit better when it begins to dull, rather than doing maintenance to keep knives really sharp consistently.

A smooth steel is better for honing, as it will just take a curled edge and straighten it, which is all you usually want to do with a truly sharp knife. Eventually the edge will begin to weaken with use, so a very fine grit ceramic rod can be used to touch up an edge (and pull off weak bits without creating a lot of jagged microserrations) if you don't want to pull out the sharpening stones.

As noted in another answer, one can usually recover from poor honing even with a ridged steel by taking the knife to be professionally sharpened (or learning to do it yourself). But harsh honing with a ridged steel is not without its costs. Subsequent sharpening will require more of the blade to be removed to return the knife to a fine edge. And with German style knives that generally have a full bolster, this can quickly lead to hollowing of the edge near the bolster, meaning that the knife will not make complete contact with the work surface. That means you need to grind down the bolster, which is more involved that simply pulling out a sharpening stone.