Chapter XXIII: A Bow

My name is spelled _AGOB_ with the order reversed.
I am marvelously fashioned and made for fighting.
When I am bent and my bosom sends forth
Its poisoned stings, I straightway prepare
5 My deadly darts to deal afar.
As soon as my master, who made me for torment,
Loosens my limbs, my length is increased
Till I vomit the venom with violent motions,
The swift-killing poison I swallowed before.
10 Not any man shall make his escape,
Not one that I spoke of shall speed from the fight,
If there falls on him first what flies from my belly.
He pays with his strength for the poisonous drink,
For the fatal cup which forfeits his life.
15 Except when fettered fast, I am useless.
Unbound I shall fail. Now find out my name.