I think the implication is that this time, no one showed up when she resurrected likely because they saw no point in fighting the hero head on. I strongly believe a monster has been following him this entire time and saw an opportunity to take the sword and took it.
Also, based on the way these sorts of stories work, I strongly suspect that the holy sword can only be used by the chosen hero. That's why a random peasant guy got chosen and given the one of a kind legendary item and thus, the sword is no good to other people.
edit: also, based on that logic, the monster that stole it is probably taking the form of a little girl just to round out the harem