If you haven't heard Regina Spektor's "Samson," now would be a good time to change that. It's one of my favorite songs of all time.
One might argue that Samson's flaw abides in the fact that he was unwilling to let others help him or that he was unwilling to truly forgive himself. While these are both fine analyses, I would posit that his essential flaw was in fact his vulnerability--his willingness to trust. You're maybe thinking right now, "That's not a flaw at all!" and before I lose all credibility, I'll affirm the same: Samson's flaw is not a flaw at all. In fact, it's what makes him human, and it's what makes us care about him as an individual. I think it's really easy to see Samson just as the warrior or as the melancholy prisoner. Sometimes we look at him and think, "Man, he was so dumb to have been fooled by Delilah after all that." But the thing is, he was still an ordinary person; his heart beats as does mine and yours, and as I see it, he really did love Delilah. So things seemed kind of shifty from the start, but how long can cynicism really hold out before love soften resolve? I don't condone Samson's actions at all, but can I understand where he's coming from? Yeah. Is it bad to love and to want to have somebody to trust? Is the worse state to be shorn of one's strength or possessed of a stony heart?