What Am I Riddles

Question: I am the thing that is used to make your weight. What am i?

Question: What can you smell but not see. And can be deadly, too.

Question: What is red and white at home, but can never be that when it leaves?

Question: What has a face and two hands?

Question: A powerful spell, the naive knows it well; one cast at an affair for your most popular gown. No sticks, no stones, a mage sans tomes, a fight, no toil but it still breaks you down.