With all the guilds in Medieval: Total War, wouldn't it be interesting if all Catholic and Orthodox factions could get access to one additional guild: The Varangian Guild?

More or less, the Guild would allow the owner to train Viking units in their cities. First level would give access to a axemen unit slightly more powerful (and less numerous) than the Viking Raiders. Second level would give additional access to a two-handed axeunit, similar to Varangian Guard. Third level would add valour bonuses to both, and extra valour to any sword/axe unit trained in the entire kingdom.