Leeeneia, you could try the "arthritis handshake" - a sort of clasping of the forearms. I know someone who is able to teach/demonstrate this very graciously to people who look like they might squeeze her hand.

I've heard that the original handshake was like this, so that the people who were meeting could size up each others' health by feeling for lymph nodes. But checking for knives might aid your health in a more immediate way ...