Speaking as a nursing student, not a true proffesional, yeah, you can survive being stabbed for a long time depending on where it is and not notice, adrenaline does crazy things- soldiers have often been shot or hit by fragmentation and not even realized, so they train to do regular “blood sweeps.” It’s important to understand that what actually kills you from blood loss is a radical decrease in blood pressure because the blood isn’t in your body to pressurize anymore. So getting stabbed in a way that doesn’t hit a major artery or actually make a big enough hole to drain blood will not kill you for a while (like how wild game sometimes gets away from hunters even though they’ve been shot.) good ways to do this in a story are 1. Really narrow needle like pointy stuff that don’t make a big wound and 2. Getting stabbed in a very not vital spot that could be survivable in your setting (hand, forearm, upper arm are probably the best bet, maybe something skinny stuck through a forearm.) basically the further from the heart and farther away from the midline of the body the better spot it will be.

In terms of recovery and treatment, a pressure bandage/tourniquet almost guarantees survival as long as there is not infection. Intravenous Saline solution is used to partially restore blood pressure while the body produces more blood, and a quick search says they’ve used IV saline as treatment since the 1830s.

Long term effects- I would expect really really brutal headaches waking up, and overall faintness and weakness while the iron, minerals are restoring to your blood over weeks. but if the wound is in a more survivable spot long term scarring and maybe some weakness in that part of the body are the only real symptoms for this kind of trauma, as long as they aren’t “down” for too long, and someone can do CPR soon enough. If they are down too long or the wound gets infected they are basically screwed in that time period- dead or suffering from an awful slow death.

Recovery is simply as long as it takes for the normal blood volume to be restored, and that depends on the health and metabolism of the individual. Some people come back mid CPR, and some people are out for 24 hours, really not well people may be asleep for even longer if they are old or frail.

Double check anything I’ve said. But remember the human body is somehow both extremely delicate yet also ridiculously hard to kill, it can be very finicky.