Arthur: Mordred calling Wiglaf a "Stable Boy" has thrown me for the biggest loop of my life. Which is saying a lot, since Wiglaf has thrown me into several physical loops.

Arthur in the distance “Wait come back! Let me love youuuuuu……”

Stable Boy Lackey, in his chainmail shirt! Actually, that's likely why he doesn't wear anything underneath that thing, it's easier to clean the chainmail and himself in a river than it would be to clean the cloth. Especially since that chainmail is likely immune to rusting.

...I don't think that counts as a spoiler. The possibility of it rusting was never brought up in the original, unless it was in an Author's Comment I didn't read. And if the armour could rust easily, it would do so the first time Wiglaf, sorry, Stable Boy Lackey, was outside in the rain. If turning on the Sprinkler System was a kryptonite of someone a Supervillain considered an annoyance, they'd be a joke instead.