3.5 out of 5 stars.

I like them. They're simple but not sloppy, and they remind me of something you'd see in an old pirate game. I also like how the transparent red skull looks normal with a light background but creepy with a dark background, like something's watching you from the shadows.
I don't know about the transparent skull with black eyes though. It would just blend into a dark background.
Also, in the diagonal resize, move, and Bone 2 cursors, you used double-thick diagonal lines and that makes the edges look too dark.