Keith,
I believe it could work for a fixed blade, but only a smaller one, say maybe 3 1/2" blade or smaller. A larger one wpuld most likely be impractical and uncomfortable.
For a fixed blade, I'd either put a 1/2" welt under the line of stitching that goes around the knife itself, or add another layer of leather to the whole sheath with the blade shape cut out of it, acting as a welt. May have to do some experimenting with this.
I've worn this sheath for the last week, including while driving a truck from NJ-Tenn. and back in the last 4 days and it has not gotten in the way or banged around the way some sheaths do whem a big guy(fat) like me wears them.
Thanks for the nice words guys.