Jambiya blade question

[Devadatta]

Hello gentlemen,

Long time I'm interested why do some jambiyas have this ornament at the blade just near the handle? I saw several alike, unfortunatelly a yemeni-craftsman couldn't explain (at least I didn't understand him) when I visited Yemen. Any ideas?

http://s45.radikal.ru/i109/1007/3f/40fff9d24a74.jpg

[Lew]

More decorative I would think I have seen it on a few jambiya myself. It could possibly cause some friction with the scabbard holding the dagger in better?