A knife in a dream can point to a threat you sense but haven't named, or to a truth that feels sharp enough to cut through pretense. Holding the knife yourself often reflects a decision to cut ties with something, while facing one aimed at you may point to feeling exposed or attacked.
The dominant star being in the Midheaven, exalted or in its domicile and taking part of the ascendant. - Picatrix (Andalusia, ~1000.AD)