Riddle 23

Wob is my name turned back;
I am a wonderfully created thing, shaped for battle.
When I bend, and from my bosom sails
a poisonous sting, I am always ready
so that I sweep that mortal affliction far away from me.      5
When my maker, he who shaped that torment,
looses my limbs, I am longer than before,
until I spit, corrupt by destruction,
the cunning venom that I took in before.
What I speak about here does not                                           10
easily pass away from anyone,
if that which flies from my womb strikes him,
so that with might he buys that evil drink
full payment with his life.
Unbound, I will not serve anyone                                            15
unless expertly tied. Say what I am called.