Putting together a Sweboz army?

[Tollheit]

and the archers, Skutjanz, just seem to cut through most opposition in the early game.

That's because most of the early opposition were Germanic units and therefore had less armour than a naked man. Skutjanz won't perform as well against Neitos etc.
If you must use archers, use some decent Baltic Medjinikos. They have more men, much better range and nearly twice as much ammo, better armour and better morale to boot. I'd still prefer some Iaosatae, though.

Helpful are IMHO (in ascending order of usefulness, pre reform units):

- some kind of Dugundiz, proven spearmen (can hold a line in melee, decent anti-cav unit, versatile)
- Woithiz Watha, Silengian grime fans (fear effect, good morale)
- Korodrougos, Oksywie swordsmen (high lethality, good number of men)
- Xerunoudozez, Germanic swordsmen (high lethality, at least some inkling of armour)
- Sloxonez, clubmen (ap)
- Kirwinikos, Baltic axemen (ap, above average lethality)
- Jugundiz Xathjiska, Chatti youth (ap, cheap as chips)
- Worgozez, those mercenary dudes with wolf pelts and axes (ap, above average lethality, fear effect)
- your FM's bodyguard
- Druxtiz Basterniska, Bastarnae warband (ap, excellent lethality)
- Marslugoi Lugjiskoi, Lugian swordsmen (ap, superb lethality, boosts morale of friendly units)