The thumb area on the blade, looks uncomfortable. Could you do a different option there?
It looks like it would be hard on a thumb. Lots of sharp edges.
Nate if I understand the concept what you call the thumb area is for the index finger. When grasped properly it's an extension of the index finger for precise work around the eyes, lips, antlers/horns, and ears. It's not designed for heavy pressure with the thumb.