Maria,
Welcome to the forum. I may be able to contribute a small bit to your understanding.
The arrow looks like the type used in Papua New Guinea. I was there for a few months a couple of years ago, and the unfletched arrows are still in common use. They are used for hunting small game, mainly birds and as a general weapon. In Port Morsby I met a man who was the night guard at a expat club who used bow and arrow as his arms. He mentioned one recent night that he had shot and wounded a man who was attempting a to hijack a car near the club. I'm sure his aim would have been fatal had he so chosen.A night shot just to wound at 50-m is impressive. He was of an ethnic group noted for their skill.
See this link for a recent news item.
http://www.nzherald.co.nz/nz/news/ar...ectid=10735245
This link is more ethnically related as to the various typesof arrow points.
http://www.art-pacific.com/artifacts...s/bowarrow.htm
There are several native art shops in Port Morsby where you can possible mail order other examples. Also the national museum there may be able to help.
The bow uses a flat piece of bark about 3/8 in. wide, I think, as a bow string to fit to the arrow that has no nock.
Good luck with your research.
Regards,
Ed