The only thing you really have to worry about here is the big blade. If you can avoid that, you'll be fine. Yes, you have to jump and shoot her in the head when she drops her guard, but you must not stand too close when you try this because the blade may hit you when she tosses it.
After she tosses the blade, stay on the ground and get ready to jump. Listen for the sound the blade makes when it rolls at you. When you hear that sound, it's coming. If you're caught tight between the blade and the edge, watch for the sparks that appear at the bottom of the blade as they will appear just before the sound comes. When you see the sparks, it's time to jump. Once you're over the blade, it's possible to hit her when she starts to jump, so keep shooting.
If you're close to the edge when she jumps into the air, run towards the center. Otherwise, you might get pinned way too close to the edge. Don't worry if she lands on you, just back off before she tosses the blade. If you do get pinned too close to the edge, you can use your ninjutsu to nullify her attack. The ninjutsu will take off two of her six health.
The best time to hit her is right after she tosses the blade but before it hits the ground, since she tosses it rather high. The most important thing is to take your time.
ALTERNATIVE STRATEGY
This is nearly useless but can be rather fun. You don't have to throw any shurikens and, if you do it right, you won't have to jump.
The object is to get her back to the edge. On her first jump, she lands nearer to the left edge so you want to be on the right side. When she comes down, get in a crouch and stay there. After she lands, sneak right up to her so your head is by her knee. (If she bumps you on the landing, you can usually recover but it's easier if you avoid that.) If she tosses the big blade, you want to be right up on her knee to avoid it and you must stay crouched. If you're not close enough, you'll die. If you bump into her, you'll die.
No matter if she tosses the blade or not, eventually she'll step back. Here's the trick: each time she steps back, you want to crawl one step towards her. You don't have to be very close, just make your move right when she does. If you do it correctly, she'll keep stepping back. When she reaches the edge, she falls and you win.
If you do it perfectly, you can take her down in 9 seconds.
