In plain words
Everything held as a support, from the underworld at the bottom to what is called Sakti at the top, falls away before those who take up the weapon that is the void. They are the true heroes; call them knowers of the void.
Word for word
Identify as heroes and knowers of the void those who wield the weapon of void-knowledge by which all supports, from the netherworld to Shakti, fall away.