Are you confused by a word I've used?
Vessel: In Supernatural Angels, like Demons have to posses a human body to be able to interact with humans on earth. An angels true appearance is to much for human senses. It will cause their eyes to burn out of their head if a human sees an angels true form, if they hear their true voice their ear drums will rupture. It is possible for some certain 'special' humans to hear/see and angel without being hurt.
Grace: The Angels 'soul' and source of power.
Angel Blade: Each Angel comes equipped with their own personal blade they are able to summon with their Grace. Angel Blades are one of the few things that can kill an angel