She wants to kill me

She's 18 months. She has pretty, curly hair. She laughs and smiles. And she's a lethal killing machine.
I'm sure its my fault. Her brother was only 16 months old when she was born. He was discovering how much fun it is to break stuff. He hurt himself frequently. He was feeling a little threatened by the cute little ball of baby that I had just brought into the house. So, for too much time, his sister waited for the attention she deserved while I attended to her brother.
It got better for her around 6 months when I adjusted to the craziness that comes from having two kids close in age. But perhaps it was too little, too late. My daughter is angry.
She has major tantrums, taking her from sweet little angel to DEMONIC WILD THING. She throws her head to the hard floors in the store, kicks and punches me to properly convey how totally hurt and upset she is that she cannot continue to take merchandise off of the shelves. She will fight so hard when being put into the car (when she'd rather be let go to run into the street) that I have almost dropped her several times. I don't even want to get into what diaper changes are like for us. Lets just say that both mommy and baby consistently need bathtime immediately afterwards.
As harrowing as these experiences can be, I don't mind them because I know what to expect during her tantrum times. Its the unexpected attacks that rattle me to the bone.
Submitted as the latest example of said attacks:
My son hates eating. He would rather snap his plastic fork in half than place any sustinance in his mouth. And two days ago, that's exactly what he did. I was upset. I wished he could eat like his sister. She sits in the booster chair next to him, systematically placing ziti noodles into her mouth, without the use of a fork. I don't always give her one - it tends to make a mess. So as I come back to the kitchen table with seconds for myself and my husband, I fail to notice that my daughter has decided a fork would be nice - she had reached across the table and obtained the top half of the broken fork, sharp edges and all.
Time passes. Meals are cleaned up. And as I pick up my daughter, she secretly takes hold of the sharp fork-weapon - and like something out of a Hitchcock movie, makes a quick stab at my neck. Unfortunately for her, she only succeeded in giving me a 3 inch long scrape, extending from my ear downwards towards the center of my neck. If only she had used a newly sharpened steak knife, or used a different technique - more of a stab than a scrape. Or if she had only studied the locations of the major neck arteries...
This time around she only succeeded in giving me a lifelong scar. It only bled a little. And now she has to deal with me for a little longer until she can plan the next attack.
My daughter wants to kill me. And I'm not pleased. Perhaps I should give her a timeout?

-Angry Housemom