Very nice presentation, F! Please also add putatively "lesser" pieces as often enough much can be learned from those, too.
Those 4 examples all look like good, antique blades to me - congrats! Did you source all from within the PI? (All 3 scabbards appear to be post-WW2, with the first 2 of quite recent manufacture as suggested by the other forumites already.)
I'm with Detlef that the hilt #4 is from water buffalo as well as probably the scabbard #3 (the metal on the latter is aluminium, I assume?).
Could you please post close-ups of the base of the blade (and pommel, too)?
I'd suggest discussing each of these pieces in dedicated threads for in-depth analysis - otherwise it will get confusing in no time...
Regards,
Kai