How did Midna get her fused shadow

Why didn't Zant take the Fused Shadows from Midna when he comfronted her next to Lanayru?

He DID take them. You don't get them back until you defeat Zant. After the battle, remember seeing how the pieces hover from him and then around Midna? This is also how Midna impaled Zant with her hair after the battle and why she couldn't do so before. It is at this point in the game where all the 4 pieces are assembled, granting Midna the power to destroy the barrier around Hyrule Castle allowing them to confront Ganondorf. This does not explain everything though and it isn't necessarily correct. However, most of the theories here are supported by something concrete from the game.

What about the piece on Midna's head? Of course, he didn't need to take it because Link and Midna needed all four pieces to win over Ganondorf, and this Zant knew. But taking three out of four still seems like a weird decision IMO.

But then again, Nintendo probably just left it there as it is the icon of Midna -- or however you would call it.

Seeing all the plot holes from Nintendo, this subject really doesn't surface questions.
I've come custom to it, I suppose.
Although, answers would be nice.

[Xytox]

Well, we're not really looking for answers, just smart and innovative theories. It's impossible to answer something that isn't in the story itself, of course. Just fun to discuss something and be creative.

Here's something: Maybe Midna kept the fused shadow minimized like she did the other ones and didn't let Zant know that she had them when she left?

I remember seeing her take it out during the same cut scene from when she was banished from the Twili Castle.

[Maetheus]

She bought it at Magic Wares Corp. and Zant stole them because he's the CEO and thought Midna was a bad customer.

Duh.

[Cryzeu]

Why didn't Zant take the Fused Shadows from Midna when he comfronted her next to Lanayru?

He DID take them. You don't get them back until you defeat Zant. After the battle, remember seeing how the pieces hover from him and then around Midna? This is also how Midna impaled Zant with her hair after the battle and why she couldn't do so before. It is at this point in the game where all the 4 pieces are assembled, granting Midna the power to destroy the barrier around Hyrule Castle allowing them to confront Ganondorf. This does not explain everything though and it isn't necessarily correct. However, most of the theories here are supported by something concrete from the game.

What about the piece on Midna's head? Of course, he didn't need to take it because Link and Midna needed all four pieces to win over Ganondorf, and this Zant knew. But taking three out of four still seems like a weird decision IMO.

But then again, Nintendo probably just left it there as it is the icon of Midna -- or however you would call it.

Uhmm... I didn't take that into consideration at all... I'm an idiot =/
But yeah, that he didn't take all 4 pieces seems incredibly stupid... I guess Nintendo wanted, like you said, let her keep it as it is iconic for her character. However, i wouldn't mind playing through part of the game where she didn't have her fused shadow on her head, during the cutscene where Zant cursed her and she walked away without wearing the fused shadow, she looked pretty cute in my opinion

[Midnaroxursox]

Yeah. It would have been better if she had more Fused Shadow-less scenes.
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AND THAT'S HOW YOU TRIFORCE!

[Xytox]

Yeah, it would be so much more fitting if Midna didn't have her helmet on when Zant cursed her. "All her powers she had in her imp form came solely from the helmet; therefor she couldn't heal when Zant stole it." I could see that work. Not to mention how her helmet also is her icon for power, so taking that away from her almost feels like a must if you're supposed to weaken her.

Then on a side note: Maybe she survived as long as she did thanks to the helmet's powers before Zelda healed her?

Yeah. It would have been better if she had more Fused Shadow-less scenes.
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▲ ▲

AND THAT'S HOW YOU TRIFORCE!

Your triforce is a bit off, hero.

Nevertheless, I concur on your opinion.

[Cryzeu]

Yeah, it would be so much more fitting if Midna didn't have her helmet on when Zant cursed her. "All her powers she had in her imp form came solely from the helmet; therefor she couldn't heal when Zant stole it." I could see that work. Not to mention how her helmet also is her icon for power, so taking that away from her almost feels like a must if you're supposed to weaken her.

Then on a side note: Maybe she survived as long as she did thanks to the helmet's powers before Zelda healed her?

Well, since you were never provided with any real answers for these questions in the game i guess one can speculate very far on the matter. But i actually think i would really like the concept of her not having her fused shadow during the time between after Midna got injured to the time after you defeat Zant. However i find it difficult to come up with theories for how this would work without that contradicting other theories somehow... But what you said about how her powers as an imp came from the Fused Shadow, i think this makes sense becuase as she was walking away without it she shambled and eventually collapsed. So, maybe the curse that made her an imp actually was supposed to kill her but the Fused Shadow kept her alive? However that dosen't seem like a very efficient way to kill someone... Ugh... i'm confused...

[Xytox]

The baddies do not always want to kill people they hate an effecient way. Quite the contrary, actually. They often want to see the victim suffer until he/she is dead. So what you say could work.