Jory saw the Wardens much as Cailan did - an elite and slightly mysterious order shrouded in legend. Both had misguided notions of glory, but after encountering the darkspawn, Jory realised the reality was very different.
It's easy to dismiss him as a coward, but he has a lot to lose - a wife pregnant with a child he'll never get to see if he dies. The Warden, and indeed Daveth, have more to gain from becoming wardens, or at least, less to lose.
So whose fault is it? Jory, clearly, didn't understand what he was getting himself into, and was not cut out for being a warden. Duncan, as experienced as he was, should have seen this, and as desperate as he was for recruits, it doesn't take a genius to figure out that a man with a pregnant wife is not going to have his head in the game.
Perhaps Alistair, too, should have reported that Jory didn't take to fighting the darkspawn in the Korcari Wilds, though Alistair is himself inexperienced and could have put that down to first time nerves (after all, he tells the Warden that the first time he encountered darkspawn, he wasn't prepared for how monstrous they were).
Still, Jory should have been given an out before the ritual took place. No secrets would have been revealed at that point. Still, as he said in the game, he was eager to see the ritual. Perhaps he felt that as he had come this far, he had to see it through.
So, you could rightly say that the blame was partly Jory's for not getting out while he could, and partly Duncan's for misjudging his character. Perhaps Duncan even had doubts about Jory but went ahead anyway because he needed the recruits. That's actually more reprehensible.
Jory isn't a martyr - he is a misguided man who wasn't cut out to be a warden and paid the price. A victim? Perhaps, but one who also had a hand in his own death.