Idiot Ball = stupid for no reason but stupid. Unfounded. Deus ex machina-style stupidity.
Stupidity within the realm of normal human error in a situation that has built-in grounds for error is NOT IDIOT BALL.
If you folks had not freely and of your own will raised Zeetha up on a pedestal that canon does not support, you would know better. This is the woman who, in a berserk rage, killed an entire group of unprepared pirates who thought she was sick and weak...but forgot to question any of them. The woman who spent three years giving circus shows, NOT hiring out as a sell-sword or urban strong-arm. The woman who, oddly enough, was only spared death-by-gun-in-the-face by the fact that Gil didn't want to kill her and was carrying a flare gun in any case. Who was repeatedly surprised by Lu's strength and ability to rack up the combat points. The one whose pride and cockiness got in the way of several of those fights. She's a trained fighter, but she is NOT a vastly experienced, super-human killing machine who can't be stopped by less than the angel of death. She has never been presented as any sort of seasoned vet, much less a super ninja goddess of war. YOU made her that, and I sometimes swear I think it's because she's so sexy half naked with swords that it's too, too tempting to jack her up a few levels more and make her a Perfect Green Haired Valkyrie.
She's the woman who was indeed beaten by Klaus. Was repeatedly caught off-guard in (admittedly) a mock battle with Gil. Who needed to be TAUGHT the basic hand-to-hand martial art approach that "anything is a weapon." Who got cocksure and paid for it fighting the Beastie Horse.
If you had not imagined her as the Perfect Warrior, but had weighed canon for her flaws as well as her virtues, you would have known this was within her character shortcomings even without taking the Nepenthe and the Moveit into account.
Further, if you had taken ANY of the repeated indications of Zola's murderous potential seriously, or for that matter chosen to take the Moveit and Nepenthe, and Zeetha's lack of one weapon when she is trained for two seriously, you'd have been aware of Zola was a real threat.
Instead the Foglios played fair with you and you "lost" the round because you preferred your own sloppy head-canon to the real thing. Nu, it happens to ALL of us. We all have head-canon. But now....NOW...you have the nerve to blame THEM for handing Zeetha an idiot ball?
Do cocky young warriors with limited (or even extravagant) amounts of actual combat experience fail to treat all enemies as potential deathtraps?
Do even experienced warriors make that mistake? I suggest you attend some military or police funerals to get your answer...but I'll give you a hint: Yes.
Do circumstances like being drunk or drugged affect a fighter's judgment? Um-yup.
What about a ginned up opponent on 'ludes or steroids, or, say...moveit #11? Does that screw with a warrior's judgment? Again, I suggest you go to a few cop funerals.
It is exactly those sorts of variables that make this a completely plausible, if devastating, plot twist. Zeetha was and has always been a good show fighter with limited experience of real rough and tumble. Her one major kill-sweep was in the pirate citadel when she took out a group of people by surprise, when they weren't expecting attack from that quarter, when she was in a fighting fugue...a condition she appears not to recognize in others. She's fun, and funny, and a smart-ass, but she loves to get a quip in when she can, and she has been surprised and caught off-guard many times within canon.
She got put in a situation where exactly that set of traits were combined with her ignorance of Zola's skill level, inability to factor in the effects of drugs on herself OR Zola, and probably failure to factor in the fact that she was short a weapon.
And she got nailed. I hope she lives. But her death is not idiot ball. It's supported by the character's own personality and demonstrated skill levels, and if you had not cranked her up higher than she actually warranted, cranked Zola lower than the danger level the canon had attached to her repeatedly, and failed to accept that the situation was utterly unpredictable for the people in it, you'd know it wasn't Idiot Ball before you even trotted out the term.
You don't have to LIKE having walked into an emotional shock with a blindfold you tied around your own eyes, but it would be really nice if, just once, the Foglios could fool people appropriately without egos and emotion instantly leading to fan squalls of cheating or bad writing.
Jeez. Sometimes I swear I think the entire lot of fandom has grown so used to reruns, and the ability to quote Buffy line for line before the actual DVD makes a sound, that you've forgotten that good writing tosses you surprises and shocks every so often. They are not idiot ball if they are supported, and they are not deus ex machina if they are supported, and they are not OOC if they are supported. If the writers put in the effort to follow through on an ongoing pattern -- which ALL of this is -- then it's YOUR fault for failing to keep it in mind, not theirs for successfully surprising you anyway.