Knapped correctly, the edge of an obsidian blade is extremely sharp and therefore would have made excellent knife blades. The downside was its fragility but when it breaks, the jagged edges are still sharp and so it could be used again.
Obsidian is shiny and a flat section of the stone could have been used as a small mirror - a prehistoric compact!
3. Arrow head.
Due to its sharpness, an obsidian arrow head would pierce through the thickest of hides.
If beads of obsidian were sewn onto tunics, they would have glittered in the fire light. Making them would not have been easy as the stone flakes when hit, so this would have made them valuable items.
5. A shellfish opener.
Formed into a wedge with a thin edge, this would have been perfect for prying open oysters and other shellfish.