There is a difference between swiping the card to read all informations on it and going to charge the card with some amount of money. I dont think they will carge or reserve money on your card. I havnt flewn with etihad yet (to come in nov 2011) but I had the same terms (bring your CC to check in) with Aer Lingus, KLM, Thai Airways and China Airlines and neither of them really wanted to see the card. Like one of the previous posters said, they just want to see if you are the true holder.
BTW: Etihad wrote in my booking confirmation "Remember you need to present a copy of the credit card at check in". It doesnt say that i have to bring the card itself, but i better do

gl&hf on your trip