Weird as it sounds, the most interesting part of Sword-Thain to me is how it would work in a secrecy deck.
I mean, yeah, I know--secrecy never really worked but some of those cards really ARE very powerful. This could allow you to run two heroes to keep your threat low, sneak in a heavy hitter (and you SHOULD have a way of sneaking in a heavy-hitter if you are running secrecy), play this and BAM--you are back at three heroes. If you can pull of a resourceful as well then all the better.
The biggest problem would just be maintaining sufficient card-draw to get all the pieces together before the Encounter deck can build up too much.