Vietcong armpit trap (those holes with spikes that trap your leg when you step in them).

China had gunpowder at an early date, making explosive warheads a possibility ... Mortars are fairly simple to make once you come up with the basic idea and a need for one.

Greek Fire - (like napalm ... jellied gasoline).

I would check up on the power of a crossbow (they punched through some tough steel armor).

When Hannibal attacked with elephants, hammers with large spikes were used to puncture the skull if the animal panicked (threatening friendly forces).