ariel,
I am not really sure if janissaries were able to carry regular yatagans outside their barracks. Actually, in one of my first posts in this forum, I asked a similar question:
http://www.vikingsword.com/vb/showthread.php?t=2157
I belive they were only allowed to carry yatagan knives, legally at least. But I might be mistaken also.
I agree that yatagan was the favorite weapon of brigands, rebels and so on. But are not there many other examples of yatagans, decorated with precious gems, and were products of fine craftsmanship. I bet these were not produced for people with limited means or brigands (as long as they did not persuade the real owners to communalize them, of course
)
And for the unruly character of janissaries, well.., I can dispute against that for hours
