Board Thread:Questions and Answers/@comment-108.205.136.124-20140225234503/@comment-86.45.200.131-20140302153639

I believe when Isshin stabbed her eye, he did so with the Rending Scissors, whereas Ryuko only stabbed her with the Scissor Blade, which mightn't be powerful enough. Then again, I don't remember if Isshin used the Rending Scissors or just one blade.