I went arouind measuring several of my Khukuris that felt most comfortable to my hand. Guess I have smaller hands than I thought.
Most comfortable is 3-5/8 to 3 - 7/8. circumference.
UBE looks like wood handle from picture. Guess I could gradually sand off to the proper circumference, but that's alot of sanding, without ruining a nice knife. Don't know how that would affect the balance.