Elven blades

[Neurion]

While I prefer the more Tolkien-accurate leaf-shaped blades of Sting and Glamdring, I do find the curving blades of the majority of the elven weapons in the LotR films to be astheticaly pleasing, but I've noticed there's a bit of a problem in the film makers explanation of why most of these blades are curved.
If we accept that the curved blade is universal throughout the various elven cultures of Middle-Earth, why are Glamdring and Sting leaf-shaped?

It could be argued that since they came from Gondolin, that the Gondolindhrim had developed a unique leaf-shape style of sword, but why then, is Hadhafang, a sword supposedly created for Idril, princess of Gondolin, made in the movie's commoner "curved branch" style, when her father's sword is leaf-bladed?