I think that it is definitely on the right track. During that same Q&A I asked him if they were the physical forms of a Shard, like Atium was in Mistborn. He said he would reveal whether or not that were the case in a future book.
My thought, however, is that they might not be a part of Honor at all. At least, not Shardblades. Honorblades, which we know to be totally different, ARE part of Honor I think.
Shardblades, however, have always been somewhat sinister. The black, smoking eyes...The propensity for people to kill one another over them, their use as an engine of destruction...
If you ask me, I think they are either splinters of, or the physical form of ODIUM, and not Honor at all.