Look up trocar. A dagger.
I've reached into a live open pig.
Pulled out spleen, cut mesentary, poked intestine, sliced abdomens with little blood.
But if you cut a kidney vessel, you'll bleed out quickly, internally. A thin dagger would be best, then rotated about the small incision area.
Thinking about putting my badge on dental floss instead of lame elasto cord.
Much better weapon.
Vascular systems. To disable civilization, cut power, water, sewer, rail, or truck lines.
Simple enough. Best not to make enemies.