All that us left of Igash is a dry and vile husk, as if the body was nothing more than a shell. You collected a small piece of this husk, which might be studied further. Perhaps you should deliver it to Narfi at the Twenty-first Hall.
Igash appeared to be different than other Orcs. An unearthly fire burned behind his eyes, and when he fell to your blade, something was left behind and this husk is now an item of some consternation.
Objective 1 Collect the Dessicated Husk
Objective 2 Bring the husk to Narfi in the Twenty-first Hall.
You discovered that Igash was something more than a typical Orc and are looking for some answers to newfound questions.
Objective 3 Talk to Palmar at Anazarmekhem Palmar is at Anazarmekhem.
Narfi could give you very little information about the strange husk, but he thought that his agent, Palmar -- posted in Anazarmekhem -- may know something about the strange fire behind Igash's eyes.
The Dessicated Husk drops off the corpse of Igash the Fanatic, once you have aquired it, click on it in inventory to start the quest.