ionee24's right..Herschel admitted to his drinking habit in the past. Now...how big of problem will it be for a man in the middle of a zombie apocalypse without any alcohol nearby...I dunno. Ok..Herschel is older and probably has as much of a chance of dying due to an age related cause as a zombie. But...take away the booze and send in the zombies....Herschel grabs a gun and takes them out. Take Daryl away from Carol and she runs and grabs a board.
I'm not saying the contrary, however, give Beth a sharp object and she would only kill herself that's the reason why she qualifies as weaker than Carol to me. Not to mention, Beth and Carl are the only children (Beth to a lesser extent than Carl obviously).
For example, I love Daryl too but the hooded stranger who saved Andrea is definitely 10 times stronger than him. Just look at those zombies!