Surgebinding, in some form, already existed, it was apparently the cause of Ashyn's destruction but the beginning of the Nahel Bond specifically came after the Heralds. Ishar is said to have forced them into an organization, possibly referring to the Knights Radiant (as a social institute of Surgebinders). We also see Taln's reaction to Radiants. Stormfather mentions that the appearance of Surgebinders surprised Honor. We don't know whether Honor reworked anything about Surgebinding, and if he did what did he change. The Surges are natural manifestations on Roshar, so is their arrangement, according to Brandon. He fuelled the magic system anyway and thus could regulate it. We don't how or why Honor/humans switched sides towards one another, some fighting for the other side isn't anything noteworthy, it happened in history all the time.