She couldn't kill Sasuke because her resolve wasn't strong enough not will, now tell me would Naruto have gone thru killing him? Even after all the crimes Sasuke committed Naruto still viewed him as a freind and begged on his knees to A to spare Sasuke.
Weakminded: how many times have we seen her break down mentally?
We've also seen he mental ability force a Ino's spiritual energy out of her, when she pushed through the poison through her body and still protecting Chiyo or how about when she came to the conclusion that Sasuke was indeed an enemy of the leaf.
No one is a weak willed
Everyone has a WILL stronger than us that's why they are ninjas
And not everyone is a ninja in Konoha
So basically to become a ninja you have got to have a strong will
<div class="bbWrapper">I think the examples you guy are using for Sakura's 'strong will' was just Kishi trying to redeem her character at points but look how that turned out.<br />
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She has the will of the fodder :L<br />
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Sasuke pulled numerous 180's btw but other times he's quite absolute in his ideals.</div>