Quite handy to open letters and boxes, but not much other practical everyday use. They were originally designed more as short sword ceremonial, prestige, and magical use. These do function well as daggers and slashers, causing more damage and open wound bleeding than a traditional straight edge dagger would. Your comments about a missing guard are valid, although this one is particularly wide at the base of the hilt, giving a very solid thumb rest with a reverse style grip which is common to many knife fighting techniques.

As far as sharpening goes, I guess you've never tried one. While the curves look challenging, it actually draws quite nicely across a belt sharpener, stone, or sticks without much difference noticed from a traditional double edge dagger blade.
Enjoy!
K