@Primeless he said immunity to stun (allthough I think that would be OP).
I always take Steel Brow on my archers. They only have 90 head armor even late game unless I find the wolf-like famed helmets.
Master Archers have either Warbows or Heavy Crossbows and always Headhunter and later you may fight 2-3 at a time quite frequently.
Also a crit from Orc Warlord/Berserker with Mansplitter 2-h Axe can oneshot. Even if your brother is wearing a 300+ named helmet and has 60-70 HP.
