Ashi was sloppily written. Genndy clearly had a fantastic beginning and beautiful ending in mind, but he didn't think through how to connect those.
He literally had Scaramouche just slowly crawl to tell Aku about the the sword for like 3 minutes in 7 episodes when with this kind of character there easily could have been done something much more fun.
I think my biggest problem was the episode where Jack got his sword back because in that episode Ashi has to fend off an army of orc things to protect Jack and I thought it'd be cool if like she'd go Rambo on them or something. Honestly, why even have an army, why not just a team of super outrageous assassins whom Ashi's Mother hired? But I digress.
She just punches them. That's it. Remember how in third episode Jack prepared to face an army of beetle bots with dogs and instilled fear in fucking robots? None of that shit, she just punches an army.
Genndy really only had first 3 and last episodes in mind. Not even ghost Scotsman and his daughters shenanigans.