Or to be a tad less flamboyant: Bad Guy--BG, hurts Main Character--MC, but how?
Okay, lets take it from the top:
1. stabbed with what:
knife, pencil, sword, ice pick, toasting fork, etc.
A thin blade--like a stiletto or rapier will leave a smaller wound though deep, a scimitar leaves a wide one, broken glass from a bottle can slice and dice like a scalpel.
Which era is the MC in, what type of weapon is the BG likely to use?
2. MC stabbed where:
A: clean area--chest with heart, lungs, liver
B: dirty area--stomach, intestines, bladder, kidneys--any perforations here and waste matter gets out for a secondary infection
C: head--face, eyes, cheeks, neck
D: limbs--clipping the femoral artery inside the thigh--as thick as your thumb, and you'll bleed out in 2-3 minutes.
How long does the fight last? Quick means a fast chest stab may hit a rib and deflect worse injury. Prolonged means the BG can strike multiple times and do serious damage.
How proficient is the BG? Is s/he a pro? Drunk? On drugs? In a rage?
What about the MC? Knows self-defense? Carries a weapon too? Knows of the impending attack? Is clueless?
How does the fight play out? Both standing, one stands and one sits, BG dives from a roof onto MC below, BG cuts from under the basement stairs across MC's Achilles' tendon?
What's the MC wearing--depends on personal taste, weather, social class, job, etc. A heavy coat can take longer to stab through. Add an inner pocket with something to deflect or slow a blade and your MC is lucky.
Size and shape of BG to MC matters as well: a small person attacking a larger one would have less force.
Unconsciousness can come from the impact of a fall after an assault, or a choke hold from behind while being stabbed. If the MC goes unconscious from a bleedout, survival isn't assured.
If the victim is not quite human--werebeast, alien, etc, the organs could regenerate faster or even be missing, in different places, etc.
Yes, miracles do happen, but keep it real or the reader will wish that all the characters kick off ASAP and quit wasting time.