Writing weapons into historical romances

Kaya, my female heroine in Husband of Convenience, carries a khanjar. What is a khanjar you ask? A really awesome dagger. 

I originally looked up Egyptian daggers or Turkish daggers and this came up. The hilt can be either bone or silver, probably wooden, too. Sometimes it's inlaid with jewels or carvings. The one pictured to the left happens to be plain but there are many images online with more elaborate hilts.

Why does Kaya need to learn how to defend herself with a dagger? Somewhat uncharacteristically, her grandfather taught her so as to defend herself. Just in case. But then Kaya is an uncharacteristic woman and I adore her!

Here's slightly more from Wikipedia on the khanjar. The picture on the right is from the Wiki page.

This differs from the Oman khanjar which is more ceremonial, and a sharp J shape. But the khanjar was widely used throughout the Ottoman Empire.