HEy leapingbare,
glad my advice helped ya.  It's real easy to break those barbs off, so when I get close to my final shape, I always pressure flake them on a flat surface...never in my hand.  The shape of your hand seems perfect for breaking off the barbs and points of small arrowheads since it isn't flat.  That has helped, although I still break barbs and tips off sometimes.  It just takes practice to learn what you can get away with and what you can't.