A follow up question to this would be why did the Romans use stabbing swords in the first place. It seems to me that an eight foot spear like the hoplites used would have been more appropriate for there fighting style (being cheaper, providing better reach and just as easy to use with a shield in close ranks). This is not to say that they couldn't have had both but I am having trouble finding evidence that they used spears like this at all let alone as standard issue.