Carpets are one of the ones that can seriously hurt humans. Their stings are powerful. Some don't react to them at all, others will react violently (can even kill....kind of like a bad allergic reaction).
With carpet anemones, I would seriously invest in some rubber gloves if handling them. Better yet, don't handle them at all once they are in the tank!! Your hands may be fine, but if you touch your face, eyes, lips you could transfer toxins. You most likely won't die, but you will wish you were!!
If you do feel a burning on your hands after touching one, rinse the area with vinegar immediately (works for jellyfish stings too). This will neutralize the toxins and prevent any more damage. Then wash really good with soap and water.