In the Eila Stele, it said that the humans arrived, with dangerous powers, "Of Surges and Spren". Here's the issue. As far as we know, there weren't Honorblades until the Desolations started, and spren didn't start forming a Nahel bond after that. So, either, there were already Honorblades of some type (although I believe that when humans arrived on Roshar they were followers of Odium, so maybe Odiumblades?), or they were Surgebinding in some other way. This would also mean that there's some undiscovered-as-of-yet magic system with spren (I guess maybe that could be referring to fabrials), and that, aside from the Nahel bond and Honorblades, there's some way to Surgebind, maybe with Dawnshards. Does my logic make sense?