That Fists stunt is too broad, I think. Armed Arts only gives a couple of weapons.
It's the same stunt that Karin Murphy has in her write-up from Paranet Papers (they just call it Extensive Training in that book). It's a common choice in the games that I play/run, and I find that it's balanced in the sense that it doesn't allow ranged/thrown weapons. If you want to limit it further, you can say that it only lets you attack with HtH melee weapons (which is not really a limit for this build since she can defend with her higher Athletics skill).
If you're looking for a Pure Mortal alternative, this writeup could work.
Cassie Kane
High Concept: Silent Ninja Assassin (alternate mute Ninja Assassin)
Trouble: Cannot Speak or Read (alternate suggestion: Only Knows How to Fight, reflects limited education and exposure to the civilized world)
Background: My Parents taught me to kill
Rising Conflict: Mentored by ________ [Oracle-type streetwise detective, possibly one that needs a wheelchair/cane and/or is a good hacker]
Other Aspects: Reluctantly anti-social, Reads Body Language instead of words, School of Hard Knocks
Powers
Pure Mortal [+2 Refresh for Stunts]
Stunts:
On My Toes: +2 Alertness
Paranoid, Probably: +2 vs Surprise
Analyze Body Language: swap Alertness for Empathy to Read People
No Pain, No Gain: +1 Mild Physical Condition
Tough Stuff: 1 armor vs blunt attacks
Extensive HtH Training: swap Fists for Weapons when using HtH Wpns
Judo Training: swap Fists for Might when Grappling
Skills:
Great (+4): Alertness (Reading People 4, Detect Surprise 6, Initiative 6), Fists (HtH Weapons)
Good (+3): Athletics, Stealth
Fair (+2): Burglary, Guns (or Bows)
Average (+1): Endurance, Intimidation
Stress: Physical OOO +1 Mild, Mental OO, Social OO
Base Refresh: 6
Spent Refresh: 5
Leftover Refresh: 1
