yep me too...and the advice for the best weapon is not a Katana...but a crowbar. Andy's hatchet looks fine if u hit with the blunt side.
And no it wouldn't be the best weapon against zombie! What happend if your blade got stuck in zombie's body or head...you're fucked with your wonderful 2400$ katana...plus i think u'll need a lot of energy to decapitate several surronding zombie or slice into bones. But with fewer energy you can hit Z's head and gave them concussion pretty easily.
But, all these advices works with slow zombies...if they still are able to run (like in Dawn of the dead) we're fucked...