"Armor as in plate, or...?"

Something else is highly likely, John thinks. They are far from home. Why would anything behave as expected here?

Ellie doesn't need to say anything further. If John is on his own and needs more than two shots, he might as well save one of the bullets for himself. That has occurred to him, as he's taken in the staggering, rotting inhabitants of this world.

"If they've a helmet, I'd like to know."

A joke, but also—

It would be better to know what to expect.