Table of Contents

Magic Armor

Magic armor weight and effect on movement is determined as per the DMG 28 rule, not the PHB 36 rule. It reduces encumbrance by half (only when worn!1)), reduces bulkiness by one step, and reduces MV reduction by one step.2) Special, truly weightless armor could of course be created by the DM as a special magic item.

Sizing

Even magic plate armor will magically fit any creature of the size class it was made for. See the armor size table.

Saving throws

Falls do not count as damage in the armor's “mode”, and so magic armor does not get a bonus against saving throws for falls outside of the standard bonuses for it being magic (+2) and its plusses.3)

UA armor

Special UA armor like elfin chain and full plate is typically only available as magic items.Ex4)

1)
Armor can not be tested for magic by lifting it up, kicking it, etc. It will have normal weight/encumbrance in that case.
2)
This is one of those cases where the books just have conflicting rules. The DMG was published later, and we feel like its rule plays better than completely weightless armor. It also gives a good reason for using more types of armor than plate, since even magic plate will make the wearer lose their dexterity bonus to reaction and initiative (PHB 101).
3)
Armor's “mode” is defending against attacks from weapons, not from high weight impact damage on a large amount of its surface area at once.
4)
This is how we've chosen to implement these items. Players cannot purchase them normally. This has worked out very well.