...

Astolfo fucking loathes being sane, in Apocrypha they have a whole scene talking about how terrified they were once they had their sanity back, Saber Astolfo has two different lines telling you they hate thinking, the entirerity of their interlude they tell you they prefer who they are without their sanity, and yet, and YET, Astolfo being a Saber and thus sane is a choice. They picked a holy grail and chose to be like this. Because that’s when they’re at their strongest and Astolfo is acutely aware that normally they are weak and liable to get people killed.

Because Astolfo is someone who will always, always, pick the option that will better help others, even if it means fucking themself over. Astolfo saved Sieg knowing it’d make them despised by their allies. Astolfo lied to protect Chiron because they knew it’d bring dissent within the group, even though they also knew Vlad would be much harsher on a single foolish scapegoat. Astolfo was initially ready to let themself die rather than let Sieg get close enough to make a contract with them.

And in times of needs, Astolfo would rather be sane and miserable than weak and a liability.