"Battlebabe are about starting trouble they probably can get out of easily or with violence."
That's more or less why I thought Ken was a battlebabe. Shit hits the fan shortly after he arrives somewhere, often because he pissed the wrong person off and when he leaves, damage was done on and by both sides. That screams battlebabe to me.
For the martial arts as implanted weapon, well, it doesn't do anything but back up threats the character might be doing ("...or else you'll feel the power of the okuto technique") or when he charges into battle. It's not like he's really a one man army. He's just very effective at using violence as a tool. Since implanted is a legit tag, why not shoehorn it into the weapon creation rules ? Battlebabe weapons are highly personal and unique. You don't see them twice. Why not make them martial arts, simply by adding implanted to them ?
It's more or less the same as a move like
Okuto technique : when the player has nothing but her fist to fight, she can use them as a weapon : 3-harm hand.
(And I might add noisy or messy in there. The ma in Fist of the Northstar are pretty graphic).
But I feel it's more elegant as it follows the rules more or less as written without a big change like a custom move, and it does cost a weapon slot to the character. The thing is : is implanted really worth only one tag, or should it "cost" more, maybe a noisy or messy mandatory to the mix.