there is a razor knife that can cut photo paper holding it in one hand, or other razors, such as scalpels, that can cut through skin, fat, muscles, and arteries without applying much force
A dull razor blade won't cut your hair of your leg, which will give you an uneven shave. A dull razor blade will also give you, "razor rash," which is when you get red dots on your legs from shaving.
Pampas Grass is an ornamental grass that can grow very high and large if not kept trimmed and it's leaves are very sharp. (I should know, my arms show the scars from my battle with my pampas grass...