Hi fernado, these southern African/Zulu type spears the binding can be steel or brass wire, vegetal fibre or a dried leather/gut shrink fit method of helping to hold the blade. The true early stabbing assegai of the Zulu wars had a large blade and quite a stout haft. There are latter 19/20th cent stabbing spears with a smaller blade. There is a good chance your spear is 19th cent. This may sound silly but if it has a thin haft and feels like you could throw it then it probably is a throwing spear
Here are pictures of one I have. These are said to have be carried as a small bundle and thrown before engaging with a stabbing spear. I find it fascinating that warriors armed with these and other simple weapons gave the British army, one of the most modern in 19th cent, a jolly good hiding more than once
. Tim