DD2 is violent! Bless her, she is obviously not doing it out of malice, but she gets excited and hits peoples faces (quite hard actually - she managed to hit/poke DH hard enough to make his nose bleed all over the bed) and if she has something hard in her hand, she is more likely to do it.
She pulls hair too, to the point where she makes nearly 4yo DD1 cry. It is all done whilst grinning and giggling - she obviously just thinks people are like big toys to be hit and pulled and nipped at will.
Nursery have told me they have to hide her favourite hitting implements- rattles, wooden spoons and drumsticks- or she spends all day chasing the other babies to hit them 
Her favourite way of relaxing is with her hand in my mouth while I sing her a song and she drinks a bottle (she did the same when she was bf, we only stopped two months ago)- I don't know how we discovered this, but it is almost like an extension of that- she loves touching faces and hair.
How can I stop her doing it, as she is upsetting (and injuring) other children, but she clearly isn't aware that it hurts people, so I feel mean telling her off. I have even taken her into her bedroom with me for a minute because DD1 has insisted she should have "time out" for hitting, and I need to be consistant for DD1s sake.
Any ideas?