So just a crazy theory here. From Oathbringer we know that the Parsh were attempting to get to Feverstone Keep right before the Recreance, which is where many of the KR left their blade and plate. I think that the Parsh could have been trying to reach Honor's perpendicularity to complete the shattering that had started earlier and then they succeded. When honor was shattered that killed any spen who were currently in a nahel bond. The KR were then left with dead spren screaming at them and immediately left their blade and plate behind. The felt they had broken some sort of oath because they allowed Honor's shattering. But they did not break their nahel bond oaths. With regard to the skybreakers, it has been said that they maintained their oaths. I think it is possible however that the skybrakers who were KR at the time still abandoned their blades and plate but continued their culture and attempted to recruit new spren/acolytes with the guidance of Nale. Finally with regard to the spen who believe that the KR had broken their oaths, they would have only seen spren deaths from broken oaths prior so it is natural to assume that the spren that died were due to broken oaths. Also it is unlikely that any higher spren was present as the stay mainly in shadesmar unless part of a bond, in which case they would have died. I think this may be true as the "secret" behind the recreance seems rather underwhelming and already know among the KR and the shattering o Honor has already been linked to the recreance. So I think it is possible that instead of breaking the nahel bonds, those bonds were instead broken by Honor's shattering.