Thanks very much for the feedback and discussions so far.
An opinion without a solid stream of reasoning is useless? Depends on the context. If you are an appraiser you can't do that. You must provide your supporting evidence to support your conclusion. If you are a dealer and you are putting a premium value on an item because of reason XYZ you need to support that with evidence. All that makes perfect sense and I agree completely. But in a less rigid environment of say a think tank or a brainstorming session sometimes an unsubstantiated opinion can spark a direction which ultimately leads to the fact finding to support it. It's the chicken and the egg. Sometimes we don't have the ability to support an opinion until many, many years later. Is the world flat or round? Einsteins theory of relativity. It took many years to support the hypothesis mathematically.
In this scenario, the guessing game was intended to be fun, maybe educational and to hopefully spark some discussion. We learned about how the Javanese look at dating a blade. They don't. They use Tangguh to classify it and within that cultural context that is most important. For me personally I respect that and want to understand it. I also have a vivid imagination and thinking about the actual age of the blade sends me on a journey in my mind. What all has this blade seen. How many hands has it been exchanged. What countries has it seen. With one of the blade having the potential to be very old really sparks my imagination about what the journey of this blade has been like. Some might say that is pointless since I will never know for sure. I say it never hurts to let your imagination wander from time to time.
So perhaps a better question would have been if anyone would care to hazard a guess as to the Tangguh of these Keris again with the caveat they are from my poor pictures?