When in the downed state, if you are channeling a skill, if you are revived or rally during the channel, it will count for the corresponding weapon skill.
For example, if I am playing Ranger and try to use my 2 skill when downed, but get revived, I get launched backward by my Hornet Sting attack. This is incredibly dangerous, as I can get launched off of platforms to my death, or any number of sticky situations.