User blog comment:ImperiexSeed/The oldest being, archangel or leviathan?/@comment-76.95.86.12-20120519182004/@comment-5110811-20120521220758

What are you talking about? No angel was on Cas's side. Rachel and Balthazar both betrayed him when they found out what he was up to. When I mean connection, I'm talking about their relation with God. The archangels don't need to tap any power through him. They are self-sufficient. They have a far beyond greater grace than all angels. All other angels need to tap into the "home office" to funnel in more power. The Leviathans can intercept this.

The real question is can the Leviathans overwhelm an Archangel's immeasurably far superior grace compared to all other angels? We really don't know.

I'm basing my assessments based on what was shown. And you are basing yours based on Death's statement and Edgar killing two mook canon fodder angels. We're both speculating to be honest. But Archangels have superior feats of over-riding things you'd never expect them to such as Gods and the Colt. The Leviathans are over-rated. They have done nothing. Hunters can stop them even without the Borax as evidenced by Sam decapitating Edgar after he healed himself up from Alpha Vamp's attack. Demons can take them on as well as Crowley said at the end of "Survival of the Fittest." The angels were unprepared and didn't know what they were going up against. Which is why they were in hiding.

I doubt an army of demons can take on an Archangel. They wouldn't even think about. In fact Raphael killed a slew of demons and angels when he first appeared at the gas station.