Compared to their Swadian equivalents, the Vaegir infantry classes (I can't remember what comes before Vaegir Guard!) are marginally faster, slightly-less well-armoured, but have much more useful weapons, i.e. two-handed weapons like bardiche and greataxes (battle axes, I think).
They're much better in an all-infantry army. Stay far away from them, if you're playing vanilla M&B and have melee cavalry, because they'll just get left behind. Again, if you've taken berserkers (thank you, Mag7!), you shouldn't bother.
Also, if, for some reason, their Vaegir Marksmen friends decide to whip out their scimitars, though for the most part they wear mail hauberk, they still outpace the Guard with ease.
Maybe an army of Vaegir Guard and Swadian Infantry?
Hopefully the forthcoming update will improve on the infantries' ability to keep pace with the rest of the forces.