What do the symbols in lines 40 to 56 mean in "The Passions, An Ode For Music"?

By line 40 in the poem, Fear, Anger, Despair, and Hope have all taken their turn to try and "prove his [or her] own expressive power." In line 40, Revenge rises to take his turn, and, as he rises, he throws "his blood-stain'd sword in thunder down." The sword here is a symbol of Revenge's aggression and bloodlust.
Revenge chooses as his instrument the "war-denouncing trumpet." In the Bible, and specifically the Book of Revelation, there are seven trumpets which signal seven apocalyptic events. On the sound of the first trumpet, for example, fire and blood rain down from heaven. The following six trumpets signal asteroids crashing to earth, the oceans turning to blood, and beasts and plagues ravaging great numbers of men. Thus the trumpet in Collins's poem is a symbol of the apocalyptic scale of Revenge's "passion."
Revenge also plays upon "The doubling drum with furious heat." Historically, drums have often been played as a summons to war, and so the drum in this part of the poem symbolizes the aggression and violence associated with war. Revenge's "passion" is indeed a passion for violence, conflict, and bloodshed as indicated by the first symbol: the "blood-stain'd sword."