Hi Chris,
Further to your observations above.
It does seem that a knife was the preferred method of killing cattle, and that this was 'extended' to be the method of dispatch of choice for 'executions'.
Interestingly (as you point out), wiki in speaking about the Bandits weapons says:
"They also made famous a thin, long, and very sharp knife called a "peixeira", a fish-cleaning knife, used mostly to torture or cut the throats of their victims."
A search of google images using 'peixeira' returns some rather upsetting images. I do not recommend it!
Your point about the guards is an excellent observation and I think realistically puts to bed any notion that these guardless examples regardless of size were meant to be routinely used in 'combat' against an armed opponent. Especially in a time where firearms were commonplace.
As is the point about them denoting status. Was there a 'cut off point' where certain sizes would be specific to certain groups?
For instance, if we take this example:
It feels like something that a well dressed chap in a'frontier town' or other urban situation might carry.
These on the other hand:
Look more like they
would be at home in a gauchos belt and could be a working tool. While of course showing a noticable range of sizes. If these examples
are 'gaucho' knives, do even they denote status with their size?
Which takes us to the very large examples.
I can't find any pictures of Brazilian gauchos with knives that size, only the bandits.
Nor can I find any pictures of examples that are not captioned as belonging to bandits.
Thats not any kind of proof of course, but several sites do talk about the distinctive (rather eccentric) clothing and 'style'.
It's possible as we've just discussed, that there is a different name, and they are not actually 'faca de ponta'?
Best
Gene