By giving them a proper archer unit line they won't be so one-dimensional (which they are right now, and the only faction that is so one-dimensional) as in they have nothing but infantry to depend upon.
The archers should not be all that great I agree. A tier 5 perhaps. Perhaps make them a bit special by giving them a 2hand axe, and being pretty good at it, so they can double as an infantry. The Nords remain the best infantry faction, but they'll get much needed boost with some archery support.
I think that Nords should be all about axes. As melee weapons, they should either have an axe/shield combination or a 2-hander axe. For those without bow&arrow, for tier 4 and beyond, they should all carry throwing axes.
With strong infantry and a half decent archer unit, they can become siege specialist once again. On the field, without heavy-cavalry, horse archers, and top notch archers, they can rely on their shield wall and overwhelm the enemies with thrown axes.