“They built copper and iron shields, put sand into them, and heated them over hot fire so the sand became red-hot. By means of some mechanism they threw this sand at those who had fought bravest… The sand penetrated through the armour into the shirts, burned the body, and it could not be helped… they died, going mad with horrible pain, in sufferings piteous and unquenchable.”
With enough velocity it will still kill you.
Also gather more and heat them up.
“They built copper and iron shields, put sand into them, and heated them over hot fire so the sand became red-hot. By means of some mechanism they threw this sand at those who had fought bravest… The sand penetrated through the armour into the shirts, burned the body, and it could not be helped… they died, going mad with horrible pain, in sufferings piteous and unquenchable.”