I normally use royal icing but was looking for something a little tastier to pipe onto my sugar cookies...I found the faux fondant buttercream icing and decided to try that, it is delicious but i'm not sure how it will harden to put on cookies. Has anyone used it before? If not any other icings I can use??

I would give it a try, just out of curiosity! You're really not out that much, and you may find it works perfectly for what you want. I use a glaze icing for all my cookies, and love it. Here's the recipe:

3 cups powdered sugar, sifted
3 tablespoons skim milk (or other type milk, or water)
3 tablespoons corn syrup
15 drops brite white food color, optional (I use Americolor)

In a medium size bowl, mix together the powdered sugar, milk/water, and corn syrup until fully combined (I just use a spoon to do the mixing). Add the brite white and mix well. (The brite white seems to help prevent the icing from getting cloudy and spotty as it dries, especially when cold). Divide and color.

Note: You will want the icing to be the consistency of white school glue, or a bit thicker. If the icing is too thick, add more corn syrup. If the icing is too thin, add more powdered sugar. This icing will stay fresh for 2 to 3 weeks in the refrigerator. The decorated cookies do not need to be refrigerated. If you do not use the brite white, refrigeration is not recommended.

It's just a term used for crusting buttercream.