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What is the explanation for the odd recurved Yataghan-style bayonet popular through the second half of the 19th century? It may have been named after a Turkish sword, but it doesn't really match that pattern of blade. It isn't any stronger that a straight or single-curved blade, and its balance makes for a lousy short sword.
What many sources appear to overlook is the practicality of the design when attached to a muzzleloading rifle: it offsets the pointed tip several inches from the shooter's hand when reloading with a ramrod. Not an insignificant benefit!