i did this before but i was a noob and didn't do any pictures or anything an it just wasn't a good thread. but its dead now so here is a better version!
so here is what you do. 2 warriors fight in a one on one battle in flat terrain they are both equally skilled and have no armor but they have different weapons you vote on which one would win.
So, it seems after some reading that shuriken and kunai were ineffective weapons, only stylised to popularity in modern times and in anime. The shuriken was cut by ninjas out of scrap metal plates and ideally has four spikes, more would only have weakened its puncture force (however there were different types of kunai, some being more a throwing dart style weapon); and the kunai was a multiuse tool (e.g. used by farmers) which ninjas simply sharpened to use it as weapon.
However, if anyone would win, it would be the kunai. The objects can be avoided when thrown; and when used in close combat, a kunai is more effective than a shuriken.
The shurikan was mainly meant to make the enemy lose focus. you throw it, he have to move aside, you charge in. it was not meant by any way to kill nor injure the opponent, On the other side, the Kunai is more like a throwing knife. It can be moch more deadly, as its penetration force is quite stronger.
Both show that the "owerfull ninjas" used cheap items and were not the kind you see in anime or 80' black power movies.
Kunais are much more effective weapons since they have a proper blade that can penetrate deeper than the points on a shuriken. A kunai can be used much like a fighting knife, too.
I say spear. The only reason i say this over halberd is because, in Ancient Greece, the Spartans used spears in phalanx. Very effective and its really cool.