[Maerlande]

If you are seriously considering technical skill, then higher end heavy armour is both lighter and more mobile. I know you don't want to debate realism, but that's not my point. You could give benefit to say Ulm that the advantage of black steel is higher strength to mass ratio and much better joint design. Which is both historically and scientifically accurate. Additionally later tech armour had small geometry changes like boat hull shaped breast plates that vastly improved effective protection.

My preference with samurai armour would be to improve the defence malus and maybe even drop protection a bit. It wasn't light, but it was very mobile. However, coverage was quite uneven.

It seems to me that Dom3 is equating armour mobility to defence, mass to encumbrance, and amount of armour to protection.