A knife is a genuinely double-edged symbol in this tradition, and which edge you get depends heavily on what actually happens with it in the dream. Being cut or stabbed and bleeding connects directly to one of the more counterintuitive readings covered in the blood dream article on this site: blood in a dream is traditionally read as money, so a cut that draws visible blood is, somewhat surprisingly, read as wealth arriving rather than injury.
A knife used to threaten you, without actually cutting, reads very differently — closer to a real conflict or a sharp, pointed confrontation on the way, without the compensating "blood is money" silver lining attached to an actual wound.
Receiving a knife as a gift is read with real ambivalence by different interpreters — some read the material object positively, others point to the older idea that gifting a blade symbolically "cuts" the relationship between giver and receiver, meaning the dream can carry a warning about a relationship ending alongside any positive material reading.
Using a knife constructively — cooking, cutting food, preparing something — is read fairly neutrally, generally just reflecting practical, ordinary effort rather than carrying any of the more dramatic readings above.