About one of the swords "talking" to Harry i can't remember either.
About the Hellsword yes i mean Morgana's, it is one of those things still shrouded into much mystery.
And another point are the warden swords, they too are still not much explained. But i always had the impression that they were something that dates back to Merlin running around with a sword and somehow was created after his retreat. About the changing numbers of swords i don't have a problem with this, they are just something like power plugs one or two more or less are not important but too many would be bad. Maybe the knowledge about creating those swords makes you leader of the wardens, where Luccio hasn't found anyone worth it up to now.