Most body armor is good for 1 strike. Kevlar thread break, ceramic breaks, and you really don’t want to use dented armor, best case it’s a weak point, worst case is pushing in your chest cavity preventing you from breathing. Any body armor that is remotely mobile is effectively one time use. Now admitted (normally) used body armor can still provide some protection and can be better than nothing (except in situations where the damage impacts you, ie the plate metal being dented and pushing into your chest). And some can be repaired or replaced with the right materials and tools, but those are heavy, and take space