Hi Manolete,
Your pictures are getting finer
I think i see these being called "thee sided" or "triangular section" blades in a determined reknown British catalogue, but i can't check whether their backs are flat or concave
.
But i'd say we call it here "lamina de tres quinas e mesas concavas".
... Pick up your notions of galego
I guess in French would be called "lame à deux pans creux".