Thanks Mike.  I mostly just  used a coarse stone to sort of scrape away the rust to bring it barely to an edge and left it alone.  I suppose, if I tried, it is sharp enough to cut my finger but just barely.  I assumed that you need at least some sharpness to get between the fibers to start a split.  The top of the blade is over 1/2" thick, making a pretty heavy wedge and can take some significant whaling.   Once the weather cools off some next month, I will try again to rive some of the short logs and turning blanks I have collected. 

--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.