[Edi]

There's regular human and there's Ulm. Stronger and more durable, suck at resisting magic. As far as the str goes, I'm fine with it. Though 12 would not be out of line, it'd just be +1 to normal Ulm strength but the later eras are supposedly softer than their barbarian past. Hell, the EA Ulm women have str 11 and warriors 12, with the elites 13.

Black Knights have str 13, no reason why Guardians should not as well. Black plate infantry should probably stay at str 11. Even getting the full helmet swapped for blacksteel helmet would be an immediate +1 def.

The thing is that people often forget the str when talking about combat stats, which are usually the same across the line.