Linothorax vs Quilted linen vs spolas

[PMBardunias]

....I suspect that is an over-simplification. The stiffness is likely to be because more than one layer of leather was used ( assuming leather in the first place! ). Recall that in 17C Buff coats which were 'double layer', it was generally only the body which was 'doubled', with sleeves etc left single for ease of movement.

I don't disagree. I think it must have been either of more layers or a stiffer type of leather than the many other leather armors that are cut along the lines of a vest or coat like the Buff-coat you mention.

In addition, downward hacks with a sword/machaira would be a frequent type of blow in a close press. In addition, any blows from spear/sword which glanced off a helmet would most likely be deflected into the shoulder area...... no surprise that the shoulders were obviously considered a vulnerable area needing special protection, hence the 'yoke'.

I don't disagree that the broad shoulder pieces indicate an important protective function. In my opinion though, the driving force was the need to easily lift the arm into position for the overhand stab with the dory. I have experimented with the shoulder piece and the method of attachment seen on most early armors (a thong from the inner edge of the shoulder flap that connects near the center of the thorax) is great for this position. The flap flips up on its inner edge, which can cut into the shoulder, but doesn't hinder the arm. Because the raised arm also raises the shoulder and makes more of the weight fall upon it, it is nice that you can independantly adjust the yoke to balance this between the sides. A vest could not easily do this.

On the face of it one might wonder why the obviously stiff pteryges do not extend to cover the lower abdomen as for example later Roman ones did, which were clearly softer.

Some of this comes from a misunderstanding of what the pteruges are supposed to do. Often this is described as a "skirt", but it really is simply the protection for the abdomen. The segmentation allows for flexibility in movement of the torse. One more indication that the "tube" was quite stiff. The old bronze bell cuirasse had articulted belly plates for this function - often not worn. (yea, you all know this- its for the lurkers)