I believe all it needs is a little re-wording. It seems to be pushing it a little. Adding a more (nonchalant? Aloof? Something like that) tone to it would make it a perfect scene to add into a story. Implications, and subtle wording seem to be an area you need a bit of work on.
I like the way you've been starting out the sentences with different words each time, and not reusing any over much - it adds a bit of variety and allows no room for a monotonous tone to find it's way in. And like all things, you seem to know the exceptions to the rule, where it adds effect rather then subtract, which is even more rare.
You've managed to use first person perspective quite well, considering it's a very hard one to convey just enough emotion, in just the right way, without over doing it.
For both of the things mentioned above, I applaud you. Well done.
I've made some changes, which I believe makes the scene flow easier. Subtracted the hyphen, turned 'I' into 'I've', and rearranged things to have the subtle wording and implications I talked about earlier as an example of what I mean by it.
I feel the cold, sharp steel of the knife against my palm. Drawing out a bit of that beautiful crimson, watching it go drip drip drip on my mahogany-colored floor. Pain rushing through me, such a pleasant feeling. Oh, I've tried other things; the bottle, the pipe, but nothing is as enlightening, as blissful, as the blade. I look down at the woman on the floor, barely breathing, taped and bloody. My first playmate. My little pet.
She sits here, writhing at my feet, a look of fear plastered on her face. Tears begin rolling down her cheeks, eyes wide with terror of seeing my lovely blade. I step closer, holding her by the hair. She squirms a bit more, though her delicate, petit frame is nothing compared to my powerful build. I put my palm up to her lips, encouraging her to take in the sweet liquid. As I pull away, a bit of scarlet dribbles down her chin as she cries. Beautiful. I whisper it in her ear, and lean in to lick it clean. I take the sharp steel to her shoulders first, cutting nice, even strokes, hearing my toy's muffled shrieks and whimpers through the tape. Nothing in this world has ever felt so... right. If this was wrong, how could it feel so right? That question has been buzzing around in my brain for quite some time, and I've learned to not care. This is my purpose. This is what I was put on this Earth to do. To kill. To make this overpopulated planet a little bit safer from overflowing. You see, psychopaths aren't a curse... no, no. They are a gift from God himself. These thoughts whiz through my mind as I take the knife again, slicing it across her throat, and watching the blood run free.
She falls to the floor with a wet thud. This is the part that always makes me angry. Such... potential, gone in a flash, leaving behind blood. So much blood. Too much blood. A messy pool instead of neat little rivers. I don't like getting messy. I stand, humming to myself silently as I approach the sink. When I arrive, I take a look at the knife, seeing my reflection. And for once, I can say that I am happy in my own skin.