Hello Kukulza,
A fact is that among the Taiwan aborigines, only the Paiwan groups have traditionally the katana tip on their knives. If you can find sometimes this kind of tip among other groups, mostly among the Amis, it is because of the Paiwan group influences had on them – mostly through the Puyuma tribe.
Puyuma had a strong military organisation at the end of the 19th century, and surrounding tribes/villages were giving tributes to their chief. It’s not unfrequent to see Amis people from this area holding knives with such a tip. Here is a link to a Amis working knife with a katana tip:
http://www.formosatribal.com/show.php?item_id=34
(It is definitely a Amis knife, because of the bump on the handle, a typical Amis design that reminds me of the Dayak knives)
Well, if the ‘katana’ tip is reserved for the ceremonial/war purposes among the Paiwan, the curved tip is for working. Here after you can see a drawing of a working knife. Together with its working sheath.
Concerning the socket handle among the Paiwan, it was used before and is still, but for working knives. Please, see the pics.
Best
Nicolas