BluErf,
First of all, I must admit I don't know about "shiva keris" you are talking about. I only understand the keris. No "shiva keris" term here in Java, and I study under traditional keris tradition in Java. Just for information, here in Jogjakarta, we have a keris lovers/connoiseurs' club, called "Pametri Wiji" which is the oldest club in keris/heirloom subject in Indonesia. This club held a keris discussion every month since 1983. I joined this club in 1997, and in 2003 became the 2nd secretary. Every month, the member bring his collection to be discussed. There are at least 20 blade to be discussed every meeting. This club also held yearly keris cleansing ceremony and consultation, which I also became a part of the team since 2000. At least 200 - 400 blade cleaned every year. Since some of the members are a royal family of Jogjakarta court, I have opportunity to see and handle the first class, court made kerises, old and nem-neman ones, with reliable history, which usually unaccesible to common peoples/foreigners. So, I think I have some first-hand experience, especially in Java keris.
Now back to the subject, I haven't read Jensen's book, and I don't know what methods he use to dating the keris age. I've also found the 16th century Mataram keris in Bali, in nearly perfect condition.(In 16th centutry is the Islamic periode in Java. Majapahit had fallen in late 1400) Handling the keris by yourselves with magnifier at hand might means a lot more than just the pictures. So still I would say, the ron dha nunut is quite unusual on the old 16-17th cent. blades. The nem-neman ones, may have it since the empu wasn't follow very strictly to the dhapur's rules anymore. They make some new dhapur, sometimes a combination of two dhapur in one blade, and many of them unwritten in the old book. (dhapur means "face", that is, the blade's shape which is defined by the ricikan/details and luk it has).
The curving line connecting lambe gajah to gandhik cannot be cheated. The 16-17th cent. lambe gajah tend to look more like a torn than the lips. If there is a line, it won't be curved, but flat. Older blades (I mean the Mataram senopaten and older tangguh, late 1500 and before) have no line at all. The gandhik of nem-neman keris may look like a "smilling face", which I've never seen on older blades.
Balinesse usually polish their blade with pulverized brick, which I thought, may "eat" the blade more than lime juices. Etching quite unsual now in Bali for Balinesse themselves, and I think the skill have lost. Now usually Javanese peoples from Surabaya and Madura who done the etching. The rough profile of Java keris in fact, the criteria which is sought after by the Java collector. It's resembles the 5 sharpness (the point, 2 edges and 2 sides), symbolizing the sharpness of 5 senses. Rough blade's side might only appear if good pamor material was used. If phosporus-rich pamor material was used, it will never get rough by etching, because the pamor is also "eaten" by the lime juices, something won't happen to nickleous-rich pamor.
But anyway, a misunderstanding happen again
The "Rough" which I refered to, isn't the blade, but the transition feeling from the plain sharp edges, to the ron dha nunut/greneng serrated edges. Java keris tend to look (and feel) smoother than Bali. The greneng/ron dha nunut of Bali keris feel like a protruding thorn, ready to catch anything.
Now about carving..
Carving a keris handle is a very specialized skill. A skilled artist would only master one particular shape from his own area. If he tries to copy a handle he don't master, it is not only ended in unproper shape, but also ruining his skill and "proper shape and balance" once he mastered. In the old days, the master handle and sheath makers tried to fit the handle and sheath not only to the keris, but also to the wearer, in such way so sheath and handle would "match" the wearer's character. Today in Jogja, there is only 1, I said one, mastercarver who can carved the simple Jogja handle quite good, but still, not as good as the old one, not even the Bugis, Solo, or Bali. He is only specialized in handle making, and no other. (well, a smoking pipe might be an exception). The old day mastercarver took at least a week to make a handle, if not a whole month. It's an art, not just a handle. Asking any other carver who don't master the skill to copy the handle would never work. So asking Madura carver to copy the Bugis will never work, so does asking Tom
Sorry Tom. Asking the Bugis carver to copy Madura's Donoriko handle would also never work either. It's a very specialized, state of the art skill, not only a talent, which many of them, unfortunately, have lost.
Someone who don't live in the cultures himselves sometimes make a wrong interpretation. For instance, The Parang Rusak Batik cloth. Westerner tend to interpret "Parang" as a single-edge weapon used to slash someone neck
while "rusak" interpreted as "broken", by war, of course. So, the wearer, would be interpreted as a "war monger, blood lust" person. Unfortunately, the Java king use it as his formal dress. Interpreting "Parang" as a weapon is true only in Melayu/Indonesian language, but it isn't true in Javanese language, where the Parang Rusak motif originated. In Javanese, "Parang" might means the cliff on the sea. "Parang Rusak" means broken cliff, which might be interpreted as "you might as tough as cliff, but in the end, it is broken anyway", and for the king, interpretation might be "even the tough cliff broken, and you wouldn't be the king forever too"
Just some insight on how the cultural diffences might turn something upside down