@GreatGuardsman, the two abilities capstones that you suggested are a great idea. Also, the reasoning behind then are a very good one.
When I thought on values I was too concern that the effects would be a little too strong. But you have a good point. CON and Wits doesn't provide as good effects as the other attributes at current state. So, maybe is better to maintain STR/FIN/INT as is and add other effects to CON and Wits (and Memory).