I am starting to doubt that you even know the character you are arguing against. Gil has info analysis by merely looking at things, compounded by his massive intellect.
I mean... is not really a can of worms. She can't. She can't fly except with her mount, though she can jump really high. If she's kicking off his chain, he's even worse than I thought.
Is... simple logic? If Herc can't move, he gets killed, and Illya dies. Herc doesn't want this, he cares for Illya despite being mad, yet he is bound long enough that Illya tries to use a command spell to warp him out, she and Gil exchange banter, and then he goes slash her. Not until the last second he can pull it off. Why... would he not do something he can pull off with his normal level of strength? Simple, he can't, he just simply went beyond his limits one time. And indeed, Quetz isn't Herk, Herk is outright stronger physically. Worse, she has more Divinity, so she gets bound much harder than him.
The actual heck you mean? Pfft. Gil can still gather information perfectly on people while suppressing his future sight. He does it all the time in Stay Night, where he jobs the most, even against Shirou. I also don't remember her knowing how he fights, just kinda knowing he's there? The difference is you are saying Quetz would just pull out all these skills willy nilly when we aren't shown her fighting like this, unlike Gil who has outright statements of abusing weaknesses with the stuff he throws (like using the best treasures agaisnt Herc after a single volley to bypass God Hand).
Assuming she can even pull it off before she gets killed, maybe? Though nothing stops Gil from killing the bird too.
I really doubt you are reading anything of what I said. I could argue what someone could do with their power, but I would have to PROVE they would use the power in such a way as well. Scathach has a similar skill but the main skill she uses is Clairvoyance, not spamming every single combat-worthy skill her mana can allow. We actually see Gilgamesh do what I claim, we don't see Quetz do what you claim. Is that clear now or is your only answer still sarcasm?