I think that's actually the first nimcha/saif I've seen with a backsword blade! Very interesting. EDIT: Actually, there are a couple on the first pages of this very thread! My memory is not great. }|:oP
I've seen a few of the Manding swords with straight blades as well. Sometimes it's easy to get them confused, especially when they are not the kind with the bulbous scabbards.
Case in point:
Contrast
with: