Heyy! Sorry if this reply is coming late; I’m super bogged down with classwork/life stuff right now and so I’m on hiatus from blogging. :\
The post you’re talking about is pretty old, but no worries. I took to the wiki page on Hephaestus to see if you were right, and I didn’t see anything about Dave’s quest being confirmed to have been to wake Hephaestus. I think Denizens are separate from quests anyway. The quest is designed to promote growth, and the Denizen gives the player The Choice as a gateway to choose the path of their life and confirm their growth. If I was going to guess what Dave’s quest was, I would think that it would be something about mending a broken sword. But, of course, I could be wrong. So much of this is left up in the air, I really hope that Hussie does a neat job of wrangling it all back in to make the story a closed loop.