Thank you Timo and Alan for your explanations.
I am approaching the questions from a historical point of view and while I understand the advantages of forging a blade with an integral bolster, I am also trying to understand how this preference or technique spread in a certain area and time frame.
For almost four hundred years the yataghan type of blade in the Western Ottoman empire is forged flat, with a decorative bolster soldered or fixed to the base of the blade with an adhesive, not pinned. Ivory, horn, or metal scales are pinned to the tang to form the handle and a decorative strip is affixed around the edges of the handle.
At the same time, small cutlery in Italy and in Central Asia appears with a forged or welded bolster. In Western Europe this has late-medieval roots. Knives with integral bolster are also made in Istanbul in the 1700s.
Then at some point around 1800, or maybe earlier, we see instances of the yataghan type of blade with a forged bolster, in Anatolia, Kabylia, and Bulgaria. This method does not replace the older one, and is not related to blade size in the Bulgarian context, but in Anatolia appears to accompany large blades with T-section. The forged bolster is is not a technique used in other sword or sabre designs anywhere near the Ottoman empire at the time, but some earlier 17th century Tatar sabres seem to use it.
The sporadic adoption of this method of bladesmithing makes me wonder if we have a peculiar, itinerant group (possibly ethnic) moving around and spreading this bladesmithing technique and preference. If we do, then what is the direction of this movement?
The style of
very long and heavy yataghan with very substantial integral bolsters seems to become popular again towards the end of the 19th century in rural Anatolia. In this context it supposedly becomes a show feature, part of costume.
Emanuel