From more research on the Yakuana I found this information which I have copied and paste here;
The YeŽkuana conceive of the universe as being comprised of two parallel planes : caju (the sky) and nono (the earth). In nono, the lower plane of the universe, the supernatural was long ago neutral (or at least its manifestations were unknown to the inhabitants of the earth). Then the Sun father let three magical eggs fall down. The first two opened and from them came Wanadi, a mythical culture hero, and his brother. The third did not break open, but was smashed and deformed. Wanadi then threw it into the forest. With this second fall, the egg opened and Cajushawa, full of resentment and hatred, appeared on earth and turned into the negative manifestation of the supernatural. Since then the people of Cajushawa (the demons or odosha) have proliferated over the earth, dominating the invisible reign of the earth. In contrast, Wanadi, the benevolent expression of the supernatural, after having lived on the earth for a time during which he struggled against Cajushawa, left the earth in the hands of people, the YeŽkuana, and it is up to them to fight demons.
Full link here
https://pib.socioambiental.org/en/Povo:Ye'kwana
With that view of Yakuana cosmology I dare to hypothesize that the two prongs on the last piece I post here are representations of the two brothers, however the name of the other brother is not mentioned. If so then I would suggest that this is a Shamanic ritual weapon. Sometimes knowing why something is, is more interesting than what it appears to be.