Ah, what's in a name ??
I'm not seeing a great similarity in the tips you have illustrated .
I'd be willing to bet that the Pira you have shown in the lower right of your four examples is probably the oldest form .
The example you show above it seems to be mid 20thC; it certainly has a pira hilt but the blade seems a bit generic .
Two styles sharing the same name but very different forms ?
