Okay, I took both your advice and tested Marathon's lighter armour suggestion first on random siege games yesterday. I felt much quicker on foot than with the mail hauberk and didn't notice being much more vulnerable than I already felt. When switching to a borrowed Light Mail and Plate (because it looks flash and only weighs .5 more than the brigandine) with a kettle hat, I was noticably slower to move, but my swings didn't seem to be affected. And I think I survived a few more hits than I did in light armour.
Maybe it's just subjective. I also tried my buddy's Espada Eslavona and was surprised how often I would actually hit. That length difference really seems to do it for me. I'm slightly miffed to lose the blunt damage and knockdown possibility, because it feels as though I glance off of armour quite regularly now, even at power strike 6. Maybe it's just my poor positioning.
As for the shield.. the most important part of a shielder, I suppose. I didn't realise how incredibly vulnerable a huscarl shield is compared to a plate covered one. I thought 400 hp should be a lot, but... it seems the shield's damage reduction plays a much greater role.
Thank you guys for taking your time to answer my pesky little questions, but here's one more
From your own experience, do you think 18/18 would give my shield noticably more durability and my weapon greater speed? Would it be worth sacrificing power strike 6 and ironflesh?
Edit: As a side-question: Is it practicable at all to try riposte against polearm and two handed weapon users? I'm trying to find some way to defend against long axe fighters without relying on a shield that'll break.