[quote=Skallagrim]
Alright...yeah I was going to say as long as the sword has flexibility, a sword needs to survive impact and still retain a sharp cutting edge, is referred to as a spring. A powerful impact will temporarily deform the sword, however due to a degree of hardness it will return to its original shape (i.e straight and effective, not bent and likely to miss its mark due to an inability to travel in a perfect arc. ) This temper also allows the steel to retain enough hardness that it will generally use hold a good cutting edge when used against things like bone, wood ,and even iron.
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Ye, contrary to popular belief swords are not solid pieces of steel.