get it "metal"

Maybe he's a successful Knight who can afford to replace dented metal

I'm just a retard in a tinfoil hat.

Good armor was designed specifically to deflect attacks, since a direct puncture with a modest force could penetrate fairly easily (P=F/A). Dents, on the other hand, do the opposite. In many areas, dents can also interfere with movement, since sections are layered in a way to telescope and/or slide past each other.

Came here to ask if it should be mettle and there's already an answer, good job guest!

mettle is an old specialized spelling for metal(figurative use)

Google says it's someone's ability to cope with difficulties, is that the figurative use you meant or is that a third meaning as well?