Killing an Abomination as Absomet came to discover was difficult, you could not just behead them or cut off their limbs, if it was that simple, Absomet would have easily eradicated Lamia's horde no matter their numbers with the weapons previously available to her.
An Abomination had an unearthly vitality and few to little vital organs, they could be referred to as nothing but teeth and claws with bodies attached to them.
Slicing off their heads was useless, their heads would still have life and if they had no way to merge with their body, the head would simply grow new pairs of limbs, and their bodies would most likely grow two more heads as they adapted to their injuries.
