- Jan 2010
I find it hard to believe it penetrated the plates unless it was spring steel against iron. If both were iron it may have creased it, but edged weapons are generally useless against plate defenses, as has been shown by many modern tests. There is some debate that Lorica segmata may have been rare in the legions to begin with due to cost, possibly the harness of wealthier romans, officers, or special units
I'm not saying it's able to be done every single time, but it can be done. Plus, it would depend on the which evolution of the armour was used.
As for shoulder protection, certainly the Segmentata was superior in that respect, but segmented armour could be applied to mail for the shoulders. A reconstruction was actually made for this purpose.