Typical Hobby Knife Handles
From Top to Bottom:
This is a heaviest duty hobby knife handle I've seen. Next step up from this are utility and pocket knives. This handle can mount the largest hobby blades as well as razor saws and gouges.
This handle can mount everything the #6 handle can. The #5 is much lighter than the #6 and more comfortable for carving and sawing than the #2 handle. The #2 handles is better for general cutting.
Like the #5 and #6 handles, the #2 handle can mount the largest hobby blades.
Note that the #2, #5 and #6 handle can mount all the same blades and saws. Some #2 handles don't have a hole in the collet and can't mount razor saws or gouges.
The next three handles below the #2 are all #1 handles. I don't have a "true" #1 handle any more because the first handle below the #2 is much more comfortable — I own three of these handles. Two of them have #11 blades and one of them has a #11 saw blade (discussed with blades in the previous section). The third handle below the #2 has a chuck at both ends and was included in a chisel set.
Swivel Knife Handle
Used for cutting around curved templates such as French curves.
This handle is very small and best suited for fine detail work.