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.
Saturn should be asked for limitation of movements, hiding of secrets, impoverishment of countries, decrease of intentions, temptation of souls and water stagnation. - Picatrix (Andalusia, ~1000.AD)