[And it was clear Takumi was no Mage- his magical circuits were certainly more developed than the average human, likely a generation or two removed from a discarded Mage bastard or disinherited second child or the like. But nothing compared to the infamous mage families that usually participated in the Wars.

So it's probably not surprising when to Archer that his eyes lit up at the mention of the Servant's hate]

Good. I've seen the disasters they leave behind thanks to what my Mentor has shown me. I can't... I can't stand the idea of one of them getting a Wish or whatever secrets the Grail has...

[Rather than getting the Grail and wishing to undo or change these crimes he wanted to take the chance away from them. There was a core of spite in that logic.]