The bomb would go off, but it appears only the wing itself sustaining the effects of the necrosis.  Slowly it would eat at it, but the impact from the bomb also seemed to break the creatures arm which although helpful did not help at the moment.  The tail...cursed tails, always the problem and what Nergal was the most worried about.  

But the creature forgot about one of nergals limbs also.  Nergal was already paying close attention to the tail and as it whipped towards his right arm Nergal would shift the blades handle to the left hand, a left hand that was just as trained with the weapon as the right was.The creatures tail would whip up and wrap around nergals own right arm and in that split second the tail was busy and right before it could yank him, Nergal would use his left hand to thrust the blades tip down towards the base of the creatures jaw.  He was only be attacking at the jaws when he would be in range to do so in the first place, so the tail moving up to stop the attack would allude to being in strike range for Nergal as well.  The yank would happen a split second after the thrust.

His armor would help some on his right arm, but it would seem the creature would crush into it eventually.  The pressure of the arm being squeezed would prove to be worse for the creature as it would force the blood in his arm down towards his hand and the device that was set up to easily let it flow out when needed would not be able to stop the pressure of its force.  What blood was there would start spraying out his gauntlet beyond his control, going in random places or wherever the prater would try to fling him with the tail.

His weapon would likely be lost in the exchange, its own blood soaked handle hopefully letting its coating ooze down over the praters head that was also hopefully just stabbed.