After doing a little research ....a tang of approx. 3" seems fairly typical for a blade of around 20".
I had considered the possibillity that my blade had been shortened (hence the 4.5" tang) but the distal taper would be wrong. Seeing that the brass 'dots' seem to be placed very near the tip (on other examples shown) .....also suggests that this is no 'cut down'.
Personally I prefer the idea of a longer tang .... perhaps the forger of this blade had the same sentiments. From a practical point of view, it may make it more robust and less likely to break (part company with the handle). Is it possible that this blade had a specific use which required a stronger bond between blade and hilt.
