I have now run into this problem multiple times and I figure the solution to this problem to be trivial, but for the life of me I can not find an answer online or figure it out myself.
What I want to do is to have a movable physicalized object affect other physicalized objects, but not be affected by them. In essence have the specific objects collision response be ignore/overlap towards other movable objects but other objects that have the specific objects response channel set to block be blocked by it.Or in a simpler more abstract way: give the specific object infinite mass (I have kinda made this work in one instance but it was way adhock and still problematic).
Sample: a spaceship that pushes away debris that come into contact with it, but its own velocity/impulse would remain unchanged.
On my progress on the subject, I also encountered this problem when using the official Leap Motion plugin (the bones spaz out when hitting other movable objects), but in the community plugin with the collision enabled character this does not happen. The reason for this is yet somewhat unclear to me, but I suspect it to be something to do the hands being a skeletal mesh.