[RobT]

If I'm not mistaken celluloid is made up of layers of celluloid impregnated substrate. If that is correct, it would be unlikely to fracture as cleanly as your dagger hilt did. Bakelite however is a sort of proto plastic and fractures much the same as plastic. I would bet your hilt, if not a natural material, is bakelite. A cane collector (or better yet, a bakelite jewelry dealer) may be able to itentify the hilt material. There are usually many bakelite jewelry dealers at large antique shows. Both celluloid and bakelite are still being made. I have been told that celluloid is subject to explode if given a sharp blow and that's why celluloid billard balls were replaced by bakelite. The form of celluloid called French (or faux) ivory looks very much like ivory.
Sincerely,
RobT