Romans and Swords

[Bootsiuv]

So the Romans improved the design of the Pila? I wonder what technique they used to make it bend on impact. A soft iron, I'm sure, but how did they make it softer?

EDIT: I'm also interested in hearing the answer to Bovi's question of if a shield made them nearly useless. Wouldn't a soft iron be rather useless against a metal shield. Were most of Rome's enemies employing wooden, leather, or wicker shields, so this was seen as not much of a problem? Or did it just slice right through a metal shield, softer iron and all? *waits for a Romani expert to chime in*