Originally Posted by Lead Cenobite
It doesn't have to be easy if it's hard to come by. Besides, it's the quintessential superhero Achilles's Heel, it should be properly represented eventually if this becomes a series.
The "hard to come by" idea is nice, but think about it. Lex Luthor can acquire "hard to come by" because of his influence and riches. It makes little difference in the end.
And there are a trillion other things you can use for an Achilles' Heel. Personality traits are the best.