Anger in a dream commonly surfaces when a boundary has been crossed and the frustration around it hasn't had anywhere to go in waking life. Lashing out at someone in the dream can point to injustice you've been absorbing quietly, a reaction you've suppressed that's finally demanding to be felt, if not yet spoken.
The Scribe should be asked for manifestation of the hidden, study of mysteries, unfastening of the tongue, circulation of wealth, defamation and transmission of slanders. - Picatrix (Andalusia, ~1000.AD)