David,
I see your point. The blade is wider than typical with far more shallow luks, but when I look at the whole thing in its entirety it strikes me as archaic, even more so if it etches out to a twistcore. We can surely agree that it is at least early 19th century.
I think Battara may have a good point as well...that it is a variation of the "archaic" form.
I hate getting tied into jargon that is too "rule-making" on these type of issues because it has been my experience that every time we think we have found a line or defining feature, there can be an exception to the rule.
