Berserkir

"[F]rom that war song came a strange thing. It caused two great Danes to go berserk in their rage, and back they flew on us, their shields cast aside, and their broad axes overhead, howling and foaming as they came." &mdash; Charles W. Whistler, A Wessex Thane (cap 15)

Overall strategy
If Úlfhéðnar are the swords of the Norse, then the Berserkir are doubtlessly their hammers. Endowed with good hitpoints, and a powerful armour-piercing attack, these warriors are in essence a powerful body of warriors meant for use in assaulting enemy structures and smashing down enemy armoured formations. They still suffer from the same problems associated with the Norse "temple" units, in that they have virtually little to no armour (if compared to other units, ie [Spearmen] or Scara Infantry), but that does not matter once they close in upon their targets: Berserkir also have a powerful "fear" effect which grants them some protection when facing melee infantry - but not all. While units such as Tibetan Du-Jong or Germanic Spearmen will be affected, other infantry units such as Ghuzat Levies won't be easily cowed by the Berserkir's "fear" aura. In addition, since they are Norse units, Norse melee infantry - especially Hirdmenn - won't be easily affected. Still, the very best weapon for killing Berserkir in the open is always ranged units, to the which all factions have some access.