I don't think Maria has an intimidation factor yet. Maybe on grass, but I'm not sure. Serena still has hers for sure, while Venus' one has almost completely diminished.
JHH's one is interesting. I don't get the sense that players are scared of her right off the bat, that is they don't freeze like they do when they had to play Serena, Steffi or Venus and Martina in their heydays. However, the players do get very tight once they are about to close out the set (and especially match). They start questioning themselves "What is she going to do now? Oh no, I don't want to be on the wrong end of a comeback."
A single flow'r he sent me, since we met./All tenderly his messenger he chose;
Deep-hearted, pure, with scented dew still wet - One perfect rose.
I knew the language of the floweret;/'My fragile leaves,' it said, 'his heart enclose.'
Love long has taken for his amulet/One perfect rose.
Why is it no one ever sent me yet/One perfect limousine, do you suppose?
Ah no, it's always just my luck to get/One perfect rose.