I am developing a race of generic "barbarians", but I'm looking to see what weapons they can develop that pose a great risk to others.
I have not decided what kind of conditions they live in, and I will decide that after I see what is possible.
Assuming that forging of metal is off limits, but raw materials are limitless, what is the most dangerous weapon a barbarian could develop against bronze/iron-age foes?
An example that comes to mind is an obsidian blade. Simple, sharp, but rare due to the resources needed. For this question, ignore any limitations on what's available.