system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Why did Tony's ARC reactor allow him to resist Loki's staff?
gpt
Simply because it wasn't flesh and blood. Loki needed to touch the point of his sceptre to his target's chest. Thin cloth wouldn't impede its power, but a thick lump of various metals is as good as wearing heavy armour would be.

If Loki had thought to move his sceptre a couple of inches in any direction and try again, he'd have had Tony - but he was so nonplussed by his initial failure that Tony was able to take control of the situation and taunt Loki into throwing him out the window instead.