Could be mind over matter. If you think a rabbits foot brings luck, you will discover you are lucky when you carry the foot.
If the coat is cursed or simply has a lot of negativity surrounding it, take some sage smudge and waft the smoke all over the coat. You could also try sprinkling it with salt water, but depending on the type of coat it might not be wise. Once you cleanse it, you could try casting a luck spell or whatever kind you would like on the coat. Curses are just negative energy, don't dwell on the fear or the energy will build up again.