A Sword Maiden who survives combat and learns defense as well as offense can expect to be promoted to War Princess.
A War Princess is not a true princess though, and obviously doesn’t carry the same firepower or battle prowess as, for example, a Princess of Air.
She is still a formidable opponent, and not just because her ability scores are much more balanced.
More dangerous is her ability to Call other creatures into combat, and bolster her army with other monsters — some as powerful as her.
In fact, a wise commander will use a War Princess as a kind of gate to draw in units to battle, while other creatures maintain an offense.
The counterpoint to that is, a wise opponent will target a War Princess early in the game and remove that threat.
This is possible in part because a War Princess lacks one of the signature abilities of true princesses — Commander Defense.
So while the Maid of Machines, for example, can avoid damage while building up her army, a War Princess, as a considerably weaker unit, can only hope to dodge and parry as she draws in a full complement of warriors.