Nice "reveal".

But.
I'm not aware of any rules regarding ripping off helmets - HOW did Roy manage to do that? Anyone who ever wore a helmet will tell you that these things don't come off just like that, they're integral part of your armor!
Any helmet (regardless in which time and setting) includes straps or other measures to prevent the helmet from slipping, shifting or falling off. (At least, any helmet worth more than a carneval costume.) Helmets are not simple tin pots you put over your head!

In order to remove the helmet, you have to either
- loosen the strap while preventing the opponent to move (I guess this involves grappling rules + DEX checks in D&D).
- or cut off the strap (I guess this involves precise cuts, so DEX again)
- or ripping the helmet off your opponent (including the head!!), which involves a STR check.

Furthermore, while most medieval style helmets are padded inside, they still REQUIRE you to wear a mask like the one Tarquin has there. Wearing a helmet without a mask will give you bruises to no end, even without combat. (ok, regenerating ring > bruises, but still)

Removing the flexible mask under the helmet is in fact EASIER than removing the rigid helmet, so this should be Roys first move in the next comic.