I don't agree that it is pointless to raise their protection additionally as there is a big difference between 20 and 25 for instance. Have anyone of you even tried using legions of steel? Also iron will is pretty low level (3) and it is in the same school as gnome lore that your smiths also can cast. After that you obviously have tempering the will which is cheap and bloody excellent for Ulm, a spell that follows the nation between the ages. And don't cast it once but a lot of times as magic resistance negates it on your own troops and you probably have drain 3 when playing MA Ulm because it doesn't affect your smiths research.
And don't forget that pikes ignore shields also so it is actually not so hard to hit knights for example. They also have a morale of 11, which means that they will stay in the fight for a while raising enemies fatigue. So the thing to do is of course to have flail guys, hammerers and battle axes behind them set to hold and attack. A tip is to use the ones with less armor as they have more APs and higher defense whilst the now fatigued enemy have a lot less so they won't hit them so often anyways.
Another thing not to forget is the production bonus Ulm gets in the fortresses - so build a lot of fortresses!
Its troops only cost 10 gold anyways.