Curses are meant to harm, and are stronger than a hex. It always comes down to personal views, but some could argue a curse on one who has terribly wronged you could be for the greater good.
What you seem to be asking about is making a type of protection amulet, casting a spell to protect someone from harm. I'm not sure if there is one that doubles as a curse like 'touch this item and die' but you could try casting a spell which would only be activated when someone other than the person touches the item. However, if you're planning on charging an item with protection as well as a curse I don't think it would work as the two kind of cancel each other out.