"One of the strongest of The Consortium taken down by a child? I think not." ― Hussein
Not being a real person, Hussein is but a "Corporeal Projection" of The Consortium's leader. It was said that not only Hussein but the entire Consortium is are projections that she created and it's possible she could all have their abilities as well.
He had sought out to capture Amelia, until he was intersected by Noah who had bested him in battle prior to Noah realizing hussein's regeneration. This caused Hussein to come back to life and ultimately kill Noah, sending his soul to be claimed by Hades.
Mr. Hussein seems to have a rather maniacal, but still sane personality. He has remarkable intelligence seeing as when he devised a plan ahead of time to kill Noah and succeeded in doing so despite being killed. It should also be noted he was intelligent enough to track his targets for months before them realizing it as with Noah and Amelia.
Hussein has a blood scythe which he can summon at will. He stated that all those who are cut by this weapon will be stricken by disease to that changes along with the person it's being injected to. Mr. Oliver has been shown to possess the ability to control and manipulate blood seeing as this is how he forms his Blood Scythe. Without his enemy realizing, Hussein changed the properties of their blood to suppress their abilities. This allows for Hussein to get in quick eliminations as to not drain up his Energia or it would seem so. Mr. Hussein can seemingly heal himself, although his healing does have limits as when Noah suppressed it with Apollo's Arrow