Archangels are primordial angels that existed long before the creation of the Universe itself. They are the highest celestial beings, second only to the Primordials, and are regarded as Heaven's most fearsome wrath. The mere presence of an Archangel on Earth without a vessel can cause minor tremors, blackout the entire Eastern Seaboard, and generate strong winds and heavy rainstorms.
Being possessed by an Archangel is psychologically an Spiritually damaging to a human; some have been left in a drooling, catatonic state after possession or experienced complete breakdowns. While you don't have to worry about this since your body is your true vessel, if you choose to use someone else as a "Meatsuit," you should be aware of the consequences they may face if you don't fix them upon leaving.
All your abilities and powers, both physical and spiritual as a Seraphim, have been massively enhanced, granting you greater access to angelic abilities.
Archangels are said to possess lower-tier nigh-omnipotence. They have a tremendous and nearly unlimited power supply, known as Archangel's Grace (which is vastly more powerful and potent than an angel's grace), allowing them to accomplish almost anything they desire with a few exceptions. Examples of their power include killing lesser beings with a snap of their fingers, hand waves, or focusing their power through their eyes to cause the combustion of molecules (making them go up in flames from the inside out) or freezing them (turning them into a solid block of ice by stopping molecular movement). Gabriel can create objects out of thin air or create multiple universes based on TV shows to manipulate the Winchesters. Other abilities include Lucifer turning human souls into demons, Michael sending two humans back in time with a single touch, obliterating targets with holy energy (which can be controlled and concentrated), granting powers such as immunity to seraphic smiting or super strength, flawless resurrection and healing, near-omniscience and awareness of the universe, sensing events across time and space (including reality warping and timeline changes), energy blasts, flight, exorcism, thermokinesis, shapeshifting, clairsentience, limited precognition, power nullification, lie detection, the list goes on but it's for you to discover.
Archangels are mostly immune to the weaknesses of angels. Angel blades can only harm them, Holy Fire causes pain but is not fatal, and the Colt, which is said to kill anything, only inflicts pain. Enochian sigils have weakened effects on them.
The few remaining threats to Archangels include Archangel Blades when wielded by other Archangels, having their Grace taken (although it will regenerate over time if taken), a Ma'lak Box, and higher-level beings such as God and The Darkness.
Your angel blade and sword have been upgraded into personal Archangel Variants capable of killing an Archangel or Nephilim like Jack Kline, while keeping the vessel unharmed.
Note: As an Archangel, you can now dial back your senses to enjoy food and drink as humans do once again.