An Abomination wasn't really a lifeform of the Abyss, but rather an Astral monster.
The appearance of Abominations was quite similar to that of Humans, but their bodies were quite hideous because they had gone through some kind of mystical radiation.
This left their bodies as strong as diamond, and the cuffs on their limbs were the tools used by Balkh to control them.
Killing Abominations would definitely alert Balkh that someone was intruding into his territory.
Few people would do this because it would make their enemies more vigilant.
But Marvin decided to do the very opposite.
The two Assassins failing their task showed that Balkh had a lot of experience dealing with assassinations.
