You actually nailed the profile of a whittling knife pretty well with this. Short, stiff, with a relatively straight handle that fits the user's hand (the most important part). Typically some version of a sheepsfoot blade.
Thickness of the blade should be such that the pushing with the thumb is comfortable to the user. Length of the blade is where the leverage of the cut comes from, but too long a blade makes it unwieldy. The straight edge with the very sharp point is what allows a chip carver to create the intricate detail in a piece.
Being a bit frugal myself (read cheap SOB, lol) I have found the cable splicer's knife I carried for years to work quite well. Blades on them run about 1.25" and about .125" thick, .5"-.625" tall. Straight, rubber coated handle of roughly 5". Not even close to the quality of your blades,
@Von Gruff , but they were literally free to me, and they work when I need a carving knife. Your design, with the cutting edge below the line of the handle which is sloping away slightly, is much better than the straight line of what I'm using.
The only potential adjustments that I'd want, but this is
very subjective, is a parallel spine to the cutting edge. For me, it allows adjusting the pressure of the cut more accurately and I've found a sloping spine doesn't "feel" right for me. The only other is a more rounded butt. While I love the look and purpose of the bird beak, a whittling knife gets used in all orientations in the hand and I find the beak to get in my way too often.
I really like your work. Well thought out designs and ergonomics executed exceptionally well. Beautiful work. Thanks for sharing with us.