Concave blades

typologies like that come from many different areas and eras, so the absolute specifics vary from type to type.

Like the khopesh: it had it's shape legit because it descended from axes.

In many other cases, I'd think it's because it's a simple form for concentrating mass at the tip, thus giving the blade a strong ability to cut.

Getting behind the enemy's defence?

I'd not think so, really. A few inches of curve isn't going to magically disregard a solid closure to the line. It will certainly effect how your sword binds, and the relative length and quality of the strong and the weak, but it's not going to be some sword-periscope that reaches through guards like they're nothing.

One thing I'd mention is that they'd behave like swords with a canted tang, which would give you a longer extension from a hammer grip, but other than this point and the aforementioned effect on mass distribution, I can think of no use for this typology.

/r/SWORDS Thread