Sundew dew is fatal for humans. It will dissolve your tongue instantly and you will turn into a flesh-eating zombie within 6 hours.
I kid, I kid. It is usually relatively sweet (or doesn't taste like much of anything), and won't hurt you. I wouldn't recommend making a salad or anything, but tons of people have tasted sundew dew.
It's not really good for the leaf (it'll set that one leaf back a few days), but it won't kill your plant, and *in most cases* it shouldn't kill the leaf.
If you want to play it perfectly safe, as long as your plant has plenty of healthy growth (say, more than 5 leaves), cut a dewy leaf off, taste it, and rinse your mouth with water afterward. Then put the leaf on the surface of the soil and maybe it'll sprout a plantlet.