Friends, the oldegaffer site has a very interesting step by step. Poplar was recommended.
I purchased a Choora for Oriental Arms (many bows to Artzi!) and that scabbard had a very pleasant aroma, possibly cedar (?)
http://yeoldegaffers.com/project_scabbard.asp
The process is for a European medieval sword, but the techniques may be transferable to creating scabbards and sheathes for Jambiyas and other types of blade.
http://www.google.com/#hl=en&gs_nf=1...w=1024&bih=587