The best bead blasted G-10,hands down,Tom Krein.
I've sampled African Blackwood recently,and its pretty darn good.
Ol faithful standby great grip,durable,green canvas micarta.
If not polished too much its smooth yet pretty grippy wet,trick is not to go too polished.
A knife with a guard is a good thing,but the guard only will allow certain holds on the knife.
Take your time if you can,clean your hands if you need to.
My experience with the Kreins as well Vince.
He has really perfected the recipe over the years.
Deep enough blast with the right medium for just the right "grippiness."
Randome thoughts:
1) As mentioned, a sharp knife that allows for controlled, easy cuts will help eliminate losing your grip.
2) Blood has always been sticky to me and aided in grippiness... fish slime, when filleting; that is another deal.
3) Have a nice custom handle and want to temporarily protect it when afield
and improve grip purchase?
Cut a piece of narrow diameter bicycle tubing to length and slip it on.
