We know that honor is dead but we don't yet know what exactly happened. Here's my speculation regarding Honor's death:
It has been mentioned in the books that near the end of his life honor had become more obsessed with oaths than the true meaning behind it. He may have been overcome by his shard's intent and couldn't control it anymore. Tanavast the vessel may have then come to a tough but important decision - a decision to sacrifice himself in order to bind odium to the rosharan system (again, it has been mentioned in the books that he died doing something that bound odium to the rosharan system). Having made the decision he must have recorded the visions for a future bondsmith and made some last minute preparations to prepare humanity for the everstorm. He must have then confronted odium, making a deal with him - a deal according to which odium would be bound to the roshan system, a deal which would forbid him from harming any spren of cultivation and honor (remember odium not shattering the stormfather fearing what cultivation would do to him? We know that breaking an oath would make a hole in his soul which would render him vulnerable and easy to splinter.) and a deal which would make honor sacrifice himself (there may be a few others but I can't think of any as of now). Then, according to the deal, honor would have been splintered and cultivation must have fled, fearing that odium would splinter her too.
Or, it may have been a different version of the same thing with cultivation making the deal with odium.