TheLastOne36:
what's so good about the HRE uu?
The landsknecht doesn't give any huge advantage that makes the HRE unstoppable but think of the unique advantage given to the Khmer's balista elephant:
For field duties crossbows and pikemen are good units to have but due to the paper-rock-scissors combat system they can easily find themselves facing units that they aren't designed to deal. The landsknecht is an all-in-one unit. When it attacks it's less likely to fall foul of the combat system's choice of defender (though it's still weak against the defensive crossbows).
It's not the most powerful new unique unit - that's the [potentially overpowered] cataphract - but it's a very nice unit to have.