Women? Children? Saylors? While the above may explain some daggers, it can not explain this phenomenon as a whole.
In my view, it comes down to one thing: can the hilt fit well into the user's hand? If this is not the case, then the dagger is of little practical value! This topic is not new to this forum- see, among others
http://www.vikingsword.com/vb/showth...ht=size+matter).
Most small daggers have a small hilt. Many are too small even for a child's hand. I chose an example that is not even very small as a whole, but the hilt is far too small for the hand, even of a small person. It a Tblisi dagger from around 1900 (kindly indentified by forum members). Instead of showing my hairy hands on the forum again, I show it next to a standard-size playing card. Also, I have not seen any evidence in writing or picture of women or children carrying a small dagger. In the few pictures of children with daggers I know, they carry a full dize version.
What were they made for? Probably for some ceremonial/decorative purpose. I don't know. However, I don't think that small daggers can be easily explained by seemingly reasonable, but unrealistic arguments.
So, how big is the hilt of your shibriya? Can it be easily held in the hand?