The way each of the 3 kings define "King" is different.
But even when that is the case, they can accept the belief of certain views, but not others.
The 2 Kings before Saber make their thoughts clear to her.
No beating around the bush.
Also, Iskandar and Gilgamesh are just so badass.
Their rivalry and respect for each other is one of the highlights of the Servants in
Fate/Zero.
Now let's go the meaning of the scene - this is how I understand it:
Gilgamesh's position is that he can do whatever he wants because he's got the power to do it.
Iskandar's position is that the king should be a relatable figure, which means being things like being greedy, holding one's head up high, being a leader figure, in order to win the hearts and minds of his subjects and unify them under those common terms. Ionioi Hetairoi is walking proof that this method worked.
Saber, on the other hand, holds the view of being good will result in good things. But she was good and her kingdom fell apart anyway. She thinks she was wrong somewhere along the way, regrets and wants to do it over again.
My view on Saber's kingship.
Iskandar scolds her on how she's ignoring the reality in favor of her pretty ideals and that's why her people couldn't get on her level.
Gilgamesh finds her naivety amusing.
Iskandar dislikes how Saber regrets her kingship, and the burden she takes on as king, in his view, isn't how kingship should be. Wanting to erase everything by choosing someone else is an insult to the people who followed her to the very end since in his opinion, the King must believe in himself. So even if she pointed out to him how he had failed in his life, the point would still stand that regret isn't a thing to him.
How Gilgamesh sees Saber:
The whole scene makes it look like the only right one is Iskandar. But:
Gilgamesh's viewpoint isn't as simple as mocking Saber's ideal because he thinks it's wrong:
I believe him to be, on the spectrum of Iskandar to Arthuria, is closer to the latter. While in his youth he was tyrannical, later after he returned from his adventure, he was a wise and just king who ruled alone, by the law, for the people, and at the end died from overworking for his kingdom! Speaking from experience, he sees a "little girl" attempting to take on the responsibilities of kingship as ridiculous. To his eyes, her ideals and way of life are doomed to fail, yet she continues to fight against that inevitability. It's a stubbornness and idealism that he rarely sees, and he wants to see her struggle to attain the unattainable because of how amusing it will be. The way Gilgamesh sees her
also has a touch of admiration because Gil always likes it when a human dares to reach for impossible goals (that's why he acknowledges her kingship and tells her that there's no right or wrong answer and that she should keep going on her path - see the Novel's excerpt below). At the same time, he finds her struggle amusing because it is futile, and in his twisted way, he tries to break her to see how strongly her conviction would hold up against him.
The difference between Gilgamesh and Arthuria lies in the fact that
Arthuria let her role as a King consume her and turn her into something almost devoid of any joy and life, while King
Gilgamesh wielded that title with pride, giving respect to his subjects and demanding it in return. He was not consumed but living at his fullest the joys and hardships of being King, while Arthuria regretted becoming one. Unlike Arthuria whose kingship is more of a one-sided love which withered and died at the end, Gilgamesh sacrificed a lot for his people but in his mind, he always believes that if the king met his demise, the people in Uruk would suffer greatly! So he stayed alive for the sake of his people. Gilgamesh was a happy King and regretted nothing.
Fate/Zero Novel Volume 3, Act 10, -84:19:03
– Once upon a time, there was a man. He was a foolish and ridiculous fellow whom, despite having a body made of mud and soil, set his heart to stand shoulder to shoulder with gods.
Even to this day, the King of Heroes still couldn’t forget the way that he passed away with tears streaming down his face. ................. Like so, when he saw that man taking his last breath, the incomparable king realized – the way that this man, who was human but wanted to surpass humanity, had lived, was even more precious and more brilliant than all the treasures he had collected.
“You fool who stretch your hand towards realms not of men… There is only one person in heaven or earth who’s worthy of appreciating your destruction, and that is none other than I, Gilgamesh.
Sink into my embrace, oh you glorious and illusionary men. That is my decision.”
The golden majestic brilliance disappeared in the night mist, leaving only an evil laughter echoing long after.
Fate/Zero volume 4, final battle:
"I don’t know why you are so obsessed with some wish-granting Grail. Saber… the fact that a woman like you exists can already be considered a rare miracle, no?”
Archer’s tone was unnaturally calm, as if it was not a dangerous enemy that was before him.
"Abandon these pointless ideals and vows! These things will only restrict you and bring you misfortune. In the future, you'll need only desire me and live under my protection. In that case I vow, on my honor as King of Everything, that I will grant you all the happiness in the world."
( So... the way Gilgamesh appreciates Saber is the same way he appreciated his friend Enkidu. I never thought there was some genuine admiration in his "Saber obsession" until I've seen
Fate/Zero.
Gilgamesh wants to see exceptional things, especially people who are trying to do impossible things and have the abilities to come very close to obtaining these dreams, those who defy gods/destiny, those who never give up no matter what. Enkidu, Saber, Hakuno happened to have one of the traits that Gil admires in humans.
To Gilgamesh who believes that seeking pleasure is the proof of one's humanity, seeing Saber actively avoid seeking her own happiness is quite unsettling and fascinating to him. The difference is that, unlike in his interaction with Kirei, he doesn't let Saber make her own decision.
Saber is someone who, in Iskandar's words,
"discarded youthful romance and dreams, discarded love, and sunk into the eternal curse of ideals". Because of the way Arthuria was raised, she became "inhuman" since she discarded all her emotions; that's part of the reason Gilgamesh and Iskandar made fun of her, especially Gilgamesh seeing having desires is part of being humans so he probably sees her as a challenge to make her feel something other than regret towards her failures in life. Very very few men, if any, would be interested in a woman who didn't even have love/marriage on her list of priorities. Only Gilgamesh appreciates a woman like that. I would go for women like that, too, as oppose to those who have little dreams/ambitions and only speak the language of "romance".
Note that I'm not trying to romanticize the whole thing. Gilgamesh never truly loves Saber and is quite disrespectful toward her. The irony is that should Saber ever lose sight of her ideal, he will drop her instantly.
In all of that, it's this admiration he has for her and this part alone seems genuine. I give credit where it deserves ).