I figured out how to rework the Teutons.

Replace the Castle age armor buff with: Two Handed Swordsman upgrade Free.

OR!

Allow them to make the 2h Swordsman in the Castle age.

And give them a unique upgrade to the champion. The Imperial Champion.

OR!

Make the Teutonic knight(Elite) the upgrade to the Champion while removing the slow speed...

Give the teutons a new unique unit:

Like the Dragoon. A heavy cavalry unit that cannot be converted at all. This is reflective of their religious background.