An actual steel rod won't do much for a J-knife as a rule, since the knife will be harder than the blade. The normal use for a smooth or very lightly striated steel is to re-align the edge, which on softer steel will bend. Not remove, re-align.
Japanese knives and similar very hard steel cutting tools do not deform in use, which is why they stay sharp longer. Loss of cutting ability is due, usually, to wear at the apex or chipping away of steel. The edge rarely bends much, so a smooth steel won't do much to re-align it. A smooth borosilicate rod will do for a J-knife what a steel will do for a softer knife, and can be used with advantage IF you use very light pressure. The contact patch is quite small and even light pressure is exerting quite a bit of pressure on that tiny contact patch. Easy to exceed the material strength of the steel in the knife and chip it.
A smooth steel or borosilicate rod does NOT remove metal, it just stands the edge back up straight.
A HONING rod made of some sort of grit is another story altogether, it REMOVES steel, just like stone. Ceramic, sintered ruby, diamond coated steel, even sharp serrations or diamond cut pattern steels are HONING rods and take metal off the knife. They will indeed produce an edge, but it won't be as good, even, or polished as an edge from a stone. It's very difficult to maintain the original sharpening angle and the scratches will be diagonal or lengthwise, again different than an edge produced by a stone. With proper technique, you can keep a knife sharper than it would be without using one, but eventually the edge will become distorted and require a proper sharpening, Japanese or not.
Being a home user, I only use a steel on my carbon knives, mostly ancient and probably around RC56 or so. Keeps my Mom's K-Bar "petty" razor sharp for cutting up chickens. If my Tojiro starts to act less than perfect, I strop it on a dry 6k stone.
Peter
