With a shield you should wear less armour, that's what the shield is for.
Without a shield, armour up. I've worn plate armour for about a year now, it makes a huge difference once you learn how to counter the momentum of enemy swings so they glance all the time. Running into or away from swings can reduce the speed bonus and damage, often below plate's threshold. Then you can shrug off a dozen hits at least.
Ranged-wise, people plain old shoot you less when there are softer targets around. It's a fact.
Arrows are ignorable unless the enemy has 6+PD and MW Rus Bow-Long Bow and MW Bodkins.
Crossbows don't hurt much if it isn't MW Arbalest and MW Steel Bolts.
Throwing hurts, but use the armour to soak as much as you can so your soft teammates don't have to.