It does actually make some sense that they would have an infantry unit that can map move 2. Even if it means that army can't be actually traveling WITH the mages, it doesn't preclude them moving up as reinforcements.
If the Man at Arms, perhaps they could be given a slightly better shield, but lighter armor? I would slightly prefer the MaA to be really heavy "Imperial Guard" types, but since all of the other infantry are basically identical other than weapon, it seems the easiest way to resolve it.
While trying to avoid the "every nation should play the same" stigma that we've been battling lately, I would actually be willing to make the assertion that every nation should have at least 1 national infantry with Prot >10 that has Map Move of 2.
Flavor can get you a loooooong way, but there are other factors as well.
Hell, could even give them some kind of Levy Spear to fill the gap. It doesn't necessarily have to be their best guys.
Though, light armor + big shield appeals to me for sure.