While the Swordmaidens existed for decades, their sword style never evolved that much.
Part of it was because it was unnecessary. Most of the opponents they faced were frontier pirates, who rarely put up a great resistance when attacked up close.
Another part of it was because of the limited learning capacities of the Swordmaidens. Even if Commander Lydia set up a brutal training regime to forge desperate young girls into fearless Swordmaidens, she could not change the fact that they were not particularly smart or clever!
The third reason why the Swordmaiden Sword Style was kept simple was because the third-class swordsman mechs they piloted for most of their history did not allow for more.
Mayra had to design mechs under all kinds of limitations. The mech industry in the frontier was so barren and primitive that the mechs that emerged from this region were quite simplistic.