Another soft skill that I think could be added to the list would
charm- how to talk to people in such a way that they feel comfortable and open in one's presence. One idea for developing charm that was mentioned in the HuffingtonPost, in their article
Operation Charisma, was to go out with a friend to a public place and take turns- one person chatting up a stranger, the other watching. Afterwards, a brief discussion is held about how well it went.
Albeit, it is talking with strangers, there really is not that much that can go wrong. We don't know them, they don't know us, we don't have to see each other again. However, it can get a whole lot better, too. We never know who we might find and what conversations may turn up.