vajra scepter (ritual object of Buddhism)

to grind an iron bar down to a fine needle (idiom); fig. to persevere in a difficult task; to study diligently

enough blood flowing to float pestles (idiom); rivers of blood; blood bath

see 磨杵成針|磨杵成针[mo2 chu3 cheng2 zhen1]

If you work at it hard enough, you can grind an iron bar into a needle.; cf idiom 磨杵成針|磨杵成针, to grind an iron bar down to a fine needle (idiom); fig. to persevere in a difficult task; to study diligently