Weaknesses are kind of a lost art in superhero comics. That thing that could short circuit even the mightiest champions and lay them prey to a beatdown by the lowliest of pickpockets. Kryptonite, casting more than three hexes, man-chained braclets, being careless with where you put the hammer for more than one minute, the list was long in the old days.
For sure, in rushed or lesser authorial hands, weaknesses turned into cheap ways to make drama out of weak plots. In greater hands they made compelling stories of courage and ingenuity.
I'm not asking about stupid notions (like Hal Jordon's penchant for bonking his head, or Kent Nelson being a chump for a choke hold). What were good, character building weaknesses?
My personal fave was Snowbird. She didn't just assume a form, she mentally became that creature, and the longer she stayed in a form, the harder it was to shake off.
One of the things I loved about it never (to my knowledge) got explored: Snowbird had a human form, Anne McKenzie, Corporal, Canadian Royal Mounted Police. How much of Snowbird's attachment to our world was governed by her human form's personality?
Your fav?