Well, my general is from Reikland, but at this point my Empire army is from most of the southern Empire.
He also already has his own greatswords. And the Carroburg Greatswords. And the Reiksguard Foot.
The mercenary idea is fun and a Marienburg contingent may be in my future, but after a lot of back-and-forth thought I think I'd rather do that with some non-6E-GW models in order to convey a little bit of the foreign nature. Could be a fun whole-army project - a couple of regiments, some elites, a little bit of light cavalry, and probably some Dogs of War Duellists as recruited pirates. Oooooh the elites could be Arabyans - elite foreigners, as some Marienburger merchant doesn't trust local yokels as much as he does well-paid mercenaries. Maybe 1200 or 1500 points.
So it looks like I'm going with Middenheim for these Greatswords. I have a couple of 40k armies with a lot of blue but, as it happens, none of my Fantasy armies make much use of the color. I have a few metal Knights of the White Wolf and Todbringer, and with my army reorganization I'll have a couple of spare regiments that I can do it blue and white to match. Should be a fun project and give me a little variety.
And then...well, the last of my greenskins, and my chaos forces, and that Terrorgheist, and a few Ushabti, and maybe a Napoleonic French army...oh and that 40k Ork army that I want to build...but THEN the Marienburg mercenary force.
Thanks all for the thoughts.
Very much appreciated!