The mingling of the helms

[Urselius]

It is possible that there were other advantages to helmets made from riveted sections. Raising a whole skull and attached neck guard is technically difficult and is almost certain to introduce areas of uneven metal thickness and therefore potential weak-points. Forming half a skull, or a sixth of a skull, can be done more easily and produce a more uniform piece of metal. Also if heating and quenching were used to harden outer surfaces, then ensuring uniform heating in a forge for half a skull is much easier than for a whole skull-neckguard unit.

[Flavivs Aetivs]

I hadn't thought about it transferring the force to the rivets, good point.

I also think that the ridge piece itself, in its shape and structure would have acted like a re-enforcing bar of the earlier helmets.

I bet the ridge is what made them tough. You bring a sword down on that ridge and it's like hitting the side of an iron sheet rather than going through the flat part.

I brought that up earlier. Definitely gonna be better in taking slashing attacks with that ridge.