Among the Demons of the Dark legion, he had a reputation as an oracle, able to tell the events of past and future, and to help discover lost things, being revered in this regard and consulted by many to do predictions, even among demons lords to make important decisions, exerting considerable influence among the Dark Legion, as he was consulted before most of major undertakings, including wars, and even some monarchs outside of the Dark Legion asked for his advice, which came with hefty costs.
Some later investigators point out that the predictions of Vassagio, rather than being prophetical, were instead in nature of the vast knowledge of the past and societal studies, and that his predictions weren't pure ramblings based on magic, but informed guesses and estimations, which may have meant he worked either with the intelligence services of Paimon before the First War of the Power, and later had his own spy service, or that it was parallel to Paimon's service: However, unlike Paimon, seemingly Vassagio was more detached from demonic politics, but some claim often his prophecies were pushing a specific agenda, and that Vassagio came to be under the payroll of Satman, which Vassagio always denied.
Some investigators more inclined to the paranormal claim the predictions were magical in nature, and often modern fortune-tellers invoked Vassagio as giver of their visions.
While human demonologists said that he ruled twenty-six legions of demons, but he wasn't a military commander. Despite of these legions the demonologists claimed under his rule, sometimes human demonologists called him to be of "Good Spirit", as he was part of the more moderate factions of the demons, seeking often peace rather than war with humans, and giving as well his prophecies to anybody who paid the price he asked for them.
He often took the form of an angel.