On the northern outskirts of Vovchansk, a border soldier on the pseudo "Tikhon" received numerous injuries in close combat with Muscovites.
Brothers immediately evacuated the defender from the battlefield and took him to the hospital.
Several bullets went through, breaking the bones of both legs, and one that could have been fatal, but the bullet was stopped by the ID of a serviceman of the DPS of Ukraine.
Conclusion - the certificate should always be carried with you.
Technically you can stop bullets with just paper add glue for usability.
Leather is super durable, when you have multiple layers even more so. And most leather armor was used together with Chain mail. Its very good armor and is extremely good against stabs and cuts. Modern armored wests are either plate carrying wests (where you put metal sheets and similar in) or Kevlar in many layers, wich behaves basically like paper but is more flexible to decelerate bullets. There are also ceramic ones but idk how they work exactly.
Ceramics work by redirecting the energy of a bullet into shattering the plate rather than penetrating the vest further. This allows a plate to absorb energy across its entire surface rather than just at the point of impact, but at the cost of only working once.