In truth, Stella's reflexes were good enough. She just couldn't respond effectively and utilize her advantage since she doesn't know what to do in certain circumstances.
Even if she knows the proper stance and sword techniques, it doesn't mean that she knows when to use them…
Only experience and constant practice can help with that…
"Ashisabaki… Do you mean all those difficult footwork?" Stella asked after hearing her master.
"That's right, that was why your first exercise was to run… It wasn't just to improve your stamina but also to train your legs… Footwork requires trained legs to execute them flawlessly… We'll work on your footwork for this whole week…"
"Yes, Master!"
"Show me the shizentai…"
"Yes…"
Reiji instructed Stella. It is the natural stance where you place your left foot one foot-width to the left and one foot-length to the back… You would then lift your left heel gently to complete the form…