This happens to men too?
I thought it only happened with women. I have come across several men who hold onto my hand after a handshake, sometimes during the entire conversation. I find it funny you count this because it is so common for me, I've started to expect it.
Some men place both their hands over my hand or just give it a gentle squeeze.
I thought it was a sign of affection or an expression of closeness. I find it interesting you wondered if it was a show of dominance. Initially, even I felt intimidated but I chalked this up to culture.
As a woman, I assume its a positive sign - they are expressing some form of interest. It does gets uncomfortable for me if the man keeps making eye contact and staring when I don't reciprocate or feel the same. I do feel threatened and I think my body language also changes.
My course of action depends on the situation. If its a harmless enough man, I don't bother and just let him hold my hand.
If not, I gently twist my wrist and turn my body as if I have to make a move to leave. That is enough for the person to let go. It has never escalated beyond that.
If however it did and someone continues to hold my hand, I would politely excuse myself verbally. If that doesn't work they are violating my personal space and then I would bring out my krav maga/kickboxing skills.